build(deps): update msgspec requirement from >=0.19 to >=0.21.1

[dependabot]

Updates the requirements on msgspec to permit the latest version.

Release notes

Sourced from msgspec's releases.

Version 0.21.1

• Fix ValidationError and DecodeError raised in dec_hook being incorrectly wrapped in another ValidationError (#1013).
• Fix a potential NULL dereference in structmeta_get_module_ns (#1016).
• Fix a reference leak in ms_passes_big_int_constraints (#1017).
• Fix missing ref_template parameter in msgspec.json.schema type stub (#1002).
• Clarify order='deterministic' encoder docstrings (#1011).
• Add a porting guide for users migrating from orjson (#1007).

Changelog

Sourced from msgspec's changelog.

Version 0.21.1 (2026-04-13)

• Fix ValidationError and DecodeError raised in dec_hook being incorrectly wrapped in another ValidationError ({pr}1013).
• Fix a potential NULL dereference in structmeta_get_module_ns ({pr}1016).
• Fix a reference leak in ms_passes_big_int_constraints ({pr}1017).
• Fix missing ref_template parameter in msgspec.json.schema type stub ({pr}1002).
• Clarify order='deterministic' encoder docstrings ({pr}1011).
• Add a porting guide for users migrating from orjson ({pr}1007).

Version 0.21.0 (2026-04-08)

• Fix a segfault on Python 3.13+ that could occur when creating structs that contained a __dict__, instead of only using __slots__ ({pr}960).
• Improve type annotations for msgspec.UNSET ({pr}975).
• Fix hashing of decoded tuples on Python 3.14 ({pr}980).
• Add ref_template arg to msgspec.json.schema ({pr}983).
• Add missing libm linkage to some architectures ({pr}993).
• Fix memory leak when decoding sets ({pr}991).
• Add uniqueItems annotation to set/frozenset JSON schemas ({pr}984).
• BREAKING: Call __post_init__ from msgspec.structs.replace/copy.replace ({pr}1000).

Version 0.20.0 (2025-11-23)

• Support Python 3.14, including freethreaded mode ({pr}852, {pr}877).
• Expose the StructMeta metaclass ({pr}890, {pr}927, {pr}928, {pr}940, {pr}945).
• Add msgspec.inspect.is_struct and msgspec.inspect.is_struct_type functions for checking whether an object is a msgspec.Struct-like instance or class ({pr}950).
• Support Windows arm64 builds ({pr}943).
• Enable ThinLTO on macOS aarch64 builds ({pr}937).
• Fix leaks of re.Pattern objects when using pattern constraints of msgspec.Meta ({pr}899).
• Fixed memoryview support for msgspec.msgpack ({pr}836).
• Fix crash when typing.TypedDict contains incorrect metadata ({pr}853, {pr}947).
• Add setuptools-scm as a build dependency instead of vendoring versioneer ({pr}905).
• Remove support for legacy packaging builds ({pr}907).
• Improved the developer experience by adding the just command runner and Dev Container support ({pr}918).

Version 0.19.0 (2024-12-27)

• Improve JSON encoding performance by up to 40% ({pr}647).
• Ensure tuple and frozenset default values are treated identically whether specified by value or default_factory ({pr}653).
• Fix memory leak of match_args in StructConfig object ({pr}684).
• Fix memory leak in Raw.copy() ({pr}709).
• Update decode signatures for PEP 688 ({pr}740).
• Generate __replace__ method on Struct types, for use with copy.replace ({pr}747).
• Fix incorrect decoding of certain > 64 bit integers ({pr}751).
• Call __post_init__ when converting from an object to a Struct ({pr}752).
• BREAKING: Expand buffer when encode_into is passed a buffer smaller

... (truncated)

Commits

• 10c9ac4 Add changelog for 0.21.1 (#1020)
• 0e29058 Add porting guide for users coming from orjson (#1007)
• 88ce26d fix reference leak in ms_passes_big_int_constraints (#1017)
• bcb7a2b fix NULL check in structmeta_get_module_ns (#1016)
• 42f9184 Fix logo in README for dark and light modes (#969)
• 4ce20fa fix wrapping ValidationError and DecodeError in ValidationError in `dec...
• 20cc59d Clarify wording of order='deterministic' in encoder docstrings (#1011)
• 08edcff Update Pydantic doc links to new site structure (#1008)
• 4024c90 Add ref_tempalte to json.pyi (#1002)
• f99dca7 Update changelog for release 0.21.0 (#1001)
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot show <dependency name> ignore conditions will show all of the ignore conditions of the specified dependency
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)

[dependabot]

Labels

The following labels could not be found: bot, kind/dependencies. Please create them before Dependabot can add them to a pull request.

Please fix the above issues or remove invalid values from dependabot.yml.