Update Zig version to latest master

[hulto]

Updated the Zig version in .devcontainer/Dockerfile to 0.16.0-dev.3039+b490412cd after verifying it is the latest master version available at https://ziglang.org/download/index.json. Verified that all tests still pass with this change.

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PR created automatically by Jules for task 11810768782108773089 started by @hulto

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[github-actions]

Summary

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
2896	2896	0	0	0	0	1ms

Previous Results

Build 🏗️	Result 🧪	Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
#1918	✅	2896	2896	0	0	0	0	31.9s

Insights

Average Tests per Run	Total Flaky Tests	Total Failed	Slowest Test (p95)
2896	0	0	5m 41s

Test Changes

0 test added, 0 removed

Slowest Tests

Test 📝	Results 📊	Duration (avg) ⏱️	Duration (p95) ⏱️
eldritch-libfile: std::list_recent_impl::tests::test_list_recent_default_args	3	4m 46s	5m 41s
eldritch-libfile: std::list_recent_impl::tests::test_list_recent_default_args	3	4m 46s	5m 41s
eldritch-libfile: std::list_recent_impl::tests::test_list_recent_default_args	3	4m 46s	5m 41s
TestDockerExecutor_Build_ContextCancellation	1	5.5s	5.5s
eldritch-libsys: std::dll_inject_impl::tests::test_dll_inject_simple	1	5.1s	5.1s
TestInteractiveShell	1	5.1s	5.1s
TestOtherStreamOutput	1	5.0s	5.0s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.0s

_{🎉 No failed tests in this run. | 🍂 No flaky tests in this run.}

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