Add an action for check-links

[afshin]

This allows other repos to use skip = "check-links" and then use this action.

[codecov-commenter]

Codecov Report

Merging #97 (c617313) into master (cedc3c6) will decrease coverage by 0.12%.
The diff coverage is 42.85%.

@@            Coverage Diff             @@
##           master      #97      +/-   ##
==========================================
- Coverage   85.03%   84.91%   -0.13%     
==========================================
  Files          16       16              
  Lines        1925     1929       +4     
  Branches      242      243       +1     
==========================================
+ Hits         1637     1638       +1     
- Misses        196      198       +2     
- Partials       92       93       +1     

Impacted Files	Coverage Δ
jupyter_releaser/actions/draft_release.py	0.00% <0.00%> (ø)
jupyter_releaser/cli.py	90.83% <40.00%> (-1.07%)	⬇️
jupyter_releaser/__init__.py	100.00% <100.00%> (ø)

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[blink1073]

Thank you!