ci: use install-action to download cargo-codspeed binary

[davidhewitt]

Should cut the benchmarks job time by ~5 minutes (as well as reduce the build cache size).

[davidhewitt]

Looks like the prebuilt download failed, will retry after https://github.com/CodSpeedHQ/codspeed-rust/pull/24

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #3534 will not alter performance

_{Comparing davidhewitt:binstall-codspeed (1dca5b1) with main (abe518d)}

Summary

✅ 64 untouched benchmarks

[davidhewitt]

Still nope; https://github.com/CodSpeedHQ/codspeed-rust/issues/27