Use context manager when possible

[rfezzani]

Description

Completes #6458 refactoring.

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
• Descriptive commit messages (see below)

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.
• There is a bot to help automate backporting a PR to an older branch. For
  example, to backport to v0.19.x after merging, add the following in a PR
  comment: @meeseeksdev backport to v0.19.x
• To run benchmarks on a PR, add the run-benchmark label. To rerun, the label
  can be removed and then added again. The benchmark output can be checked in
  the "Actions" tab.

[pep8speaks]

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

• In the file doc/tools/apigen.py:

Line 470:23: E231 missing whitespace after ','
Line 506:51: E231 missing whitespace after ','

• In the file skimage/io/_plugins/fits_plugin.py:

Line 41:80: E501 line too long (80 > 79 characters)

Comment last updated at 2022-08-24 09:39:20 UTC

[lagru]

Thanks @rfezzani for completing this obvious improvement. May I suggest two more candidates:

• https://github.com/scikit-image/scikit-image/blob/main/doc/source/random_gallery.py#L52-L54
• https://github.com/scikit-image/scikit-image/blob/main/doc/tools/apigen.py#L182-L184

I don't think these are covered by #6458 which I don't want to hold up further.

Otherwise looks good! 👍

[lagru]

Thanks for addressing my suggestions. Looks ready to merge in my opinion. But perhaps we should wait until #6458 is merged to avoid merge conflicts for that first-time contribution..

[rfezzani]

Thank you @lagru.

[soupault]

Fantastic, thank you @rfezzani !

[alexdesiqueira]

Thank you @rfezzani!