Add support for returning values

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #12 will not alter performance

_{Comparing patrick91:feature/return-value (d6c492e) with master (48e4228)}

Summary

✅ 5 untouched benchmarks

[art049]

Awesome, thanks a lot @patrick91 ! This use case is super interesting to transform a test in a benchmark and benefit from the both worlds!

I don't know if it's supported in pytest-speed / pytest-benchmarks but it would be awesome to have it there as well, I might work on something :)