termcolor now disables colour if not tty, but FORCE_COLOR for colour tests

[hugovk]

Since https://github.com/termcolor/termcolor/releases/tag/2.1.0 and termcolor/termcolor#25, we need to make sure colour is enabled for these tests.

Fixes failures seen in #103, #104, #105, #106.

[codecov]

Codecov Report

Merging #107 (90f9d95) into main (45159d6) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #107      +/-   ##
==========================================
+ Coverage   95.28%   95.30%   +0.01%     
==========================================
  Files           9        9              
  Lines         382      383       +1     
==========================================
+ Hits          364      365       +1     
  Misses         18       18              

Flag	Coverage Δ
macos-latest	94.77% <100.00%> (-0.51%)	⬇️
ubuntu-latest	95.30% <100.00%> (+0.01%)	⬆️
windows-latest	95.30% <100.00%> (+0.01%)	⬆️

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Impacted Files	Coverage Δ
tests/test_norwegianblue.py	100.00% <100.00%> (ø)

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