Change strings with .format() calls to f-strings in color, exposure, transform, and util subpackages

[MariosAchilias]

Description

Partially addresses #5474

Checklist

• Docstrings for all functions
• Gallery example in ./doc/examples (new features only)
• Benchmark in ./benchmarks, if your changes aren't covered by an
  existing benchmark
• Unit tests
• Clean style in the spirit of PEP8

For reviewers

• Check that the PR title is short, concise, and will make sense 1 year
  later.
• Check that new functions are imported in corresponding __init__.py.
• Check that new features, API changes, and deprecations are mentioned in
  doc/release/release_dev.rst.

[pep8speaks]

Hello @MariosAchilias! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-08-12 12:07:02 UTC

[MariosAchilias]

I made the suggested changes. Thank you for the review.

Is there anything else I should change?

[grlee77]

The changes look good to me, but it looks like a couple files in these modules were missed (found by running grep -r ".format(" in the skimage folder):
skimage/transform/_warps.py
skimage/color/tests/test_colorconv.py

Can you please update those two here as well? Thanks

[MariosAchilias]

@grlee77 I can't find any instance of .format( in _warps.py and test_colorconv.py.

I tried running grep -r ".format(" and it doesn't show any file in those modules.

[grlee77]

I tried running grep -r ".format(" and it doesn't show any file in those modules.

Indeed, my apologies. I had not realized I ran this search on an outdated branch! This is good to merge

[grlee77]

Thanks @MariosAchilias!