Add black_box to benchmarks

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #123 will degrade performances by 5.69%

_{Comparing 121-make-use-of-black_box-in-benchmarks (5f95e62) with main (158ae2f)}

Summary

❌ 1 regressions ✅ 15 untouched benchmarks

:warning: _Please fix the performance issues or acknowledge them on CodSpeed._

Benchmarks breakdown

	Benchmark	main	121-make-use-of-black_box-in-benchmarks	Change
❌	matchit benchmarks/xitca-router	11.7 µs	12.4 µs	-5.69%

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:white_check_mark: All tests successful. No failed tests found.