bump version to 0.4.2

[davidhewitt]

Will push a patch fix for the MSRV build...

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #118 will not alter performance

_{Comparing dh/0.4.2 (d6840c6) with main (3b59df6)}

Summary

✅ 73 untouched benchmarks

[codecov[bot]]

Codecov Report

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

:loudspeaker: Thoughts on this report? Let us know!