Warn if repos.md is not properly formatted

[fthomas]

Closes #2579.

[exoego]

Ah, coverage change is not shown... 🤔
Is this already covered?

[fthomas]

The logs indicate that the report was not uploaded:

[2022-06-06T20:02:38.365Z] ['error'] There was an error running the uploader: Error uploading to [https://codecov.io:](https://codecov.io/) Error: There was an error fetching the storage URL during POST: 404 - {'detail': ErrorDetail(string='Unable to locate build via Github Actions API. Please upload with the Codecov repository upload token to resolve issue.', code='not_found')}

I'll rerun the build.

[codecov]

Codecov Report

Merging #2622 (7f137f4) into main (1f0c59e) will decrease coverage by 0.00%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##             main    #2622      +/-   ##
==========================================
- Coverage   81.10%   81.09%   -0.01%     
==========================================
  Files         144      144              
  Lines        2540     2544       +4     
  Branches       48       45       -3     
==========================================
+ Hits         2060     2063       +3     
- Misses        480      481       +1     

Impacted Files	Coverage Δ
...org/scalasteward/core/application/StewardAlg.scala	44.11% <83.33%> (+4.11%)	⬆️

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