chore: exclude benches pnpm lock file

[stormslowly]

reduce crate's size

// before
Packaged 45 files,   1.2MiB (319.9KiB compressed)
// after
Packaged 44 files, 491.3KiB (85.4KiB compressed)

because the benches's pnpm lock file is huge (766K).

[codspeed-hq]

CodSpeed Performance Report

Merging #64 will not alter performance

_{Comparing chore/exclude_bench_pnpm_lock_file (c5cbb37) with main (edbc257)}

Summary

✅ 2 untouched benchmarks