feat: bump MSRV to 1.85

[DaniPopes]

Allows usage of &mut in const fn, const {} blocks, many new standard library functions in const and runtime.

1.85 was chosen for edition 2024, and it's now 3 versions old.

Unblocks #449.

• Closes base_convert: MSRV-1.80): let as_slice = buf.as_flattened_mut(); #504
• Closes fmt: MSRV-1.67): = Self::MAX.ilog(Self::BASE) #499
• Closes [TODO] Use ilog when MSRV is 1.67 or greater #498
• Closes bytes: Use a const {} block for this assertion #283
• Closes bytes: Use a const {} block for this assertion #282
• Closes bytes: Use a const {} block for this assertion #281
• Closes support/scale: Use nightly generic const expressions to validate that BITS parameter #188
• Closes lib: BLOCKED) Many functions could be made const if a number of #88
  • I don't really know what the other features refer to, floating point is not really used
• Closes bytes: BLOCKED) Make const fns when const_for is stable. #86

[codspeed-hq]

CodSpeed Performance Report

Merging #503 will not alter performance

_{Comparing DaniPopes:msrv-1.85 (b0aed05) with main (e91a45f)¹}

Summary

✅ 351 untouched benchmarks

Footnotes

1. No successful run was found on main (b0aed05) during the generation of this report, so e91a45f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[prestwich]

stated MSRV policy is 6 months, no?

[DaniPopes]

1.85 was released on 20 February, 2025 so I'd say close enough if you round up

[prestwich]

@gakonst please don't approve PRs without reading relevant comments. This is in violation of our msrv policy as stated in the readme

[prestwich]

:)