build: add underline-color to all features flag in makefile

[joshka]

Ensures that we upload coverage details for the underline-color tests (at the expense of possible removing some coverage where the feature is not enabled). Given underline-color is a default feature this is sensible.

Also fixes up a small build warning that pops up when not building with the underline-color feature

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.2%. Comparing base (ec763af) to head (582cf4a).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1100     +/-   ##
=======================================
- Coverage   94.2%   94.2%   -0.1%     
=======================================
  Files         61      61             
  Lines      14530   14540     +10     
=======================================
+ Hits       13693   13698      +5     
- Misses       837     842      +5     

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[EdJoPaTo]

cargo hack --keep-going --feature-powerset --no-dev-deps check might be a good idea…

[joshka]

cargo hack --keep-going --feature-powerset --no-dev-deps check might be a good idea…

I agree, it's outside the scope of this change however. Let's add that sometime.

[orhun]

Agree with adding cargo-hack to the CI. Might be a good first issue even.