build: bump MSRV to v1.71

[xtqqczze]

Closes #130.
Stacked on #128.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.09%. Comparing base (3f5db7d) to head (17ea843).
⚠️ Report is 78 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #131      +/-   ##
==========================================
+ Coverage   78.64%   86.09%   +7.44%     
==========================================
  Files          13       16       +3     
  Lines        2585     3933    +1348     
  Branches      230      265      +35     
==========================================
+ Hits         2033     3386    +1353     
+ Misses        552      544       -8     
- Partials        0        3       +3     

Flag	Coverage Δ
macos_latest	85.96% <ø> (+8.32%)	⬆️
ubuntu_latest	85.53% <ø> (+7.35%)	⬆️
windows_latest	15.40% <ø> (+0.70%)	⬆️

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[codspeed]

Merging this PR will degrade performance by 8.24%

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 22 untouched benchmarks
⏩ 9 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	three 39-bit primes (u128)	769.2 ms	1,033 ms	-25.54%
⚡	five 38-bit primes (191 bits)	1.8 s	1.6 s	+13.07%

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 xtqqczze:msrv171 (17ea843) with main (4986b2e)}

Footnotes

1. 9 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. ↩