Fix publish-release

[fcollonval]

This fixes is based on using the new version to release JLab 3.4.7:

• target not pass to publish-release
  Should we pass steps_to_skip too? It seems not as there is only one step - so probably that input should be remove from standalone workflow Publish Release
• metadata.json was not ignored from the sha check loop

I created a constant storing metadata.json in util.py.

[codecov-commenter]

Codecov Report

Merging #378 (3124baf) into main (0ca050b) will increase coverage by 0.00%.
The diff coverage is 60.00%.

@@           Coverage Diff           @@
##             main     #378   +/-   ##
=======================================
  Coverage   82.57%   82.58%           
=======================================
  Files          21       21           
  Lines        2887     2888    +1     
  Branches      382      382           
=======================================
+ Hits         2384     2385    +1     
  Misses        364      364           
  Partials      139      139           

Impacted Files	Coverage Δ
jupyter_releaser/util.py	70.50% <33.33%> (+0.06%)	⬆️
jupyter_releaser/lib.py	80.82% <100.00%> (ø)

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[blink1073]

Thank you!