Ensure codespell failures fail CI

[dmathieu]

With the write option, codespell fixes issues (which is a nice behavior when we run it locally), but it also returns a 0 status code (except if some failures couldn't be fixed).

So in order to actually fix the CI on a failing codespell, we need to ensure the working directory is clean.

SDK counterpart: open-telemetry/opentelemetry-go#5761

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.5%. Comparing base (b56f243) to head (45c22f1).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #6064     +/-   ##
=======================================
- Coverage   65.5%   65.5%   -0.1%     
=======================================
  Files        203     203             
  Lines      12985   12985             
=======================================
- Hits        8508    8506      -2     
- Misses      4218    4219      +1     
- Partials     259     260      +1     

Files with missing lines	Coverage Δ
instrumentation/runtime/internal/x/x.go	100.0% <ø> (ø)

... and 1 file with indirect coverage changes