Change tabs to spaces, prepare for black

[emirkmo]

This PR changes tab indent to 4 spaces in the entire project, to prepare setting up for python black for automatic code formatting.

It also auto applies some common auto-fixable PEP8 stuff (I applied it while doing the indent changes, because why not, we strive to follow PEP8). We also change the setup.cfg for flake8 to be compatible with black and to remove tabs. Good to know that black has its own GitHub actions. So we should set up black and never worry about code formatting again for flows.
(Bonus, we can set up pre-commit hooks on e.g. GitKraken with black.

Specific changes:
Change line limit to 120 characters in setup.cfg but exact number can be discussed. Black default is 88. Project default was 99. We did not enforce it before. We should just pick something that makes it easy to read and set Black to that.

We move to a 4 space indent format.

This PR should be merged before #40 so that GitHub Actions tests can pass.

Fixes #44

[codecov]

Codecov Report

Merging #42 (42ef171) into devel (3305323) will decrease coverage by 0.19%.
The diff coverage is 22.67%.

❗ Current head 42ef171 differs from pull request most recent head 32fbb4a. Consider uploading reports for the commit 32fbb4a to get more accurate results

@@            Coverage Diff             @@
##            devel      #42      +/-   ##
==========================================
- Coverage   29.15%   28.96%   -0.20%     
==========================================
  Files          36       36              
  Lines        2627     2627              
==========================================
- Hits          766      761       -5     
- Misses       1861     1866       +5     

Impacted Files	Coverage Δ
flows/aadc_db.py	100.00% <ø> (ø)
run_catalogs.py	0.00% <ø> (ø)
run_photometry.py	0.00% <0.00%> (ø)
run_plotlc.py	0.00% <0.00%> (ø)
run_querytns.py	0.00% <0.00%> (ø)
run_upload_photometry.py	0.00% <0.00%> (ø)
run_visibility.py	0.00% <ø> (ø)
flows/run_imagematch.py	16.85% <1.44%> (ø)
flows/visibility.py	17.33% <1.58%> (ø)
flows/plots.py	12.59% <1.73%> (ø)
... and 53 more

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[emirkmo]

Closign while figuring out CI