build(deps-dev): update pybind11 requirement from >=3.0.4 to >=3.1.0

[dependabot]

Updates the requirements on pybind11 to permit the latest version.

Release notes

Sourced from pybind11's releases.

Version 3.1.0

New Features:

• Support for Python 3.8 was removed. The minimum supported version is now Python 3.9. #6110

• Support for MSVC 2017 has been dropped. #6110

• Changed strict-mode numeric conversions for PEP 484 compatibility: float now accepts int, and complex now accepts int and float. #5879

• Small extra features added to the pybind11 command line tool based on python-config. #4272

• Added subinterpreter_thread_state, an RAII wrapper that owns a reusable PyThreadState for a sub-interpreter, together with a subinterpreter_scoped_activate overload that activates it. This lets an OS thread re-enter one or more sub-interpreters without creating and destroying a PyThreadState on every activation. #6073

• Add py::mod_gil_used() as replacement spelling to py::mod_gil_not_used(false). #5797

Bug fixes:

• Fixed a crash in py::subinterpreter::create() when called without a current PyThreadState, which its documentation explicitly allows — for example from an embedder that ended initialization with PyEval_SaveThread(), or from a worker thread that has never touched Python. error_scope is now constructed after a thread state has been attached instead of before. #6127

• Make py::print delegate to the current frame/interpreter built-ins print entry, fixing handling of sys.stdout = None, following the active runtime's stream, keyword, and error semantics, and remaining a no-op if the entry is unavailable during teardown. #6121

• Include the builtin complex type in the input annotation of the std::complex<T> type caster. #6113

• String views (e.g. std::string_view) are now kept alive only when loaded from a transient source (such as a generator), fixing both a use-after-free and a regression where casting a view from a durable object outside a bound function would throw. #6096

• Drop Python 2 prepend to evaluated source, causing errors to be off by one. #6089

• Fix data race on last_storage_ptr_ cache in gil_safe_call_once_and_store. #6087

• Allow user defined __str__ on enum_. #6078

• Fix generated Callable type annotations for Python callbacks passed into C++ by inverting the callback's argument/return I/O context relative to the enclosing function signature. #6055

• Correct __delitem__ for negative-step slices and re-enable contiguous erase fast path. #6088

• Do not pass -fno-fat-lto-objects to GCC on macOS, which made all LTO probes fail and silently disabled LTO. #6114

• Fixed cross-compilation to Emscripten/Pyodide with CMake ≥ 4.1 by no longer overriding an explicitly set PYBIND11_USE_CROSSCOMPILING when CMAKE_CROSSCOMPILING_EMULATOR is defined. #6094

• Unset stale PYTHON_MODULE_DEBUG_POSTFIX and correct USE_PYTHON_INCLUDE_DIR variable. #6086

• Apply -undefined dynamic_lookup to all Apple platforms. #6075

Internal:

• Improved py::enum_ operator performance by restoring type-specific implementations. #5887

• Optimized internal std::unordered_map/std::unordered_set hashing paths with noexcept. #5960

CI:

... (truncated)

Changelog

Sourced from pybind11's changelog.

Version 3.1.0 (August 6, 2026)

New Features:

• Support for Python 3.8 was removed. The minimum supported version is now Python 3.9. #6110

• Support for MSVC 2017 has been dropped. #6110

• Changed strict-mode numeric conversions for PEP 484 compatibility: float now accepts int, and complex now accepts int and float. #5879

• Small extra features added to the pybind11 command line tool based on python-config. #4272

• Added subinterpreter_thread_state, an RAII wrapper that owns a reusable PyThreadState for a sub-interpreter, together with a subinterpreter_scoped_activate overload that activates it. This lets an OS thread re-enter one or more sub-interpreters without creating and destroying a PyThreadState on every activation. #6073

• Add py::mod_gil_used() as replacement spelling to py::mod_gil_not_used(false). #5797

Bug fixes:

• Fixed a crash in py::subinterpreter::create() when called without a current PyThreadState, which its documentation explicitly allows — for example from an embedder that ended initialization with PyEval_SaveThread(), or from a worker thread that has never touched Python. error_scope is now constructed after a thread state has been attached instead of before. #6127

• Make py::print delegate to the current frame/interpreter built-ins print entry, fixing handling of sys.stdout = None, following the active runtime's stream, keyword, and error semantics, and remaining a no-op if the entry is unavailable during teardown. #6121

• Include the builtin complex type in the input annotation of the std::complex<T> type caster. #6113

• String views (e.g. std::string_view) are now kept alive only when loaded from a transient source (such as a generator), fixing both a use-after-free and a regression where casting a view from a durable object outside a bound function would throw. #6096

• Drop Python 2 prepend to evaluated source, causing errors to be off by one. #6089

• Fix data race on last_storage_ptr_ cache in gil_safe_call_once_and_store. #6087

... (truncated)

Commits

• 97bf890 chore: prepare 3.1.0 release (#6125)
• 05f6e6f fix(subinterpreter): don't touch the thread state before create() attaches on...
• 6dd1756 chore(deps): update pre-commit hooks (#6126)
• 5956509 Delegate py::print to Python's native print (#6121)
• 63d627c feat!: drop support for Python 3.8, MSVC 2017 (#6110)
• 695a7a4 chore(deps): bump the actions group with 3 updates (#6119)
• ea9e6e6 feat: small command line helpers for quick tests (#4272)
• 652c694 fix: add py::mod_gil_used() spelling, support pedantic tests (#5797)
• 2f85cc8 chore(ci): bump NVHPC to 26.5 (#6117)
• 5540f96 fix: only add string_view life support for transient sources (#6096)
• Additional commits viewable in compare view

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