chore: make clippy happy

[mattsse]

removed all clippy warnings

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 77.76%. Comparing base (46e266c) to head (5b2468b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
ssz/src/bitfield.rs	33.33%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #35   +/-   ##
=======================================
  Coverage   77.76%   77.76%           
=======================================
  Files          12       12           
  Lines         715      715           
=======================================
  Hits          556      556           
  Misses        159      159           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[michaelsproul]

Looks good, thanks!

I've opened an issue so we don't forget to add Clippy on CI:

• Clippy on CI #36