MSRV check and policy documentation

[robert3005]

Instead of doing the work to handle new checks when we update msrv we can
benefit from them as they're released. This requires an msrv check to make sure
we are still compliant with the declared version

[codspeed-hq]

Merging this PR will regress 1 benchmark

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 5 improved benchmarks
❌ 1 regressed benchmark
✅ 1956 untouched benchmarks
⏩ 89 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	chunked_varbin_opt_to_varbinview_builder[(10, 100)]	542.8 µs	630.4 µs	-13.89%
⚡	Simulation	compact_sliced[(16384, 10)]	2 ms	1.4 ms	+39.01%
⚡	Simulation	compact_sliced[(4096, 10)]	528 µs	386.8 µs	+36.5%
⚡	Simulation	filter_one_false[250000]	210 µs	188.4 µs	+11.5%
⚡	Simulation	chunked_dict_primitive_canonical_into[u32, (1000, 10, 100)]	1.5 ms	1.4 ms	+11.46%
⚡	Simulation	chunked_varbinview_canonical_into[(100, 100)]	701.5 µs	637.5 µs	+10.04%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing rk/msrv (bd0a81f) with develop (11c0a31)}

Footnotes

1. 89 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩