ci: Add pub publish --dry-run for Flutter package

[Nidal-Bakir]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Closes: #847

Approach

start a job to check for any errors when running dart pub publish --dry-run For the Flutter package

TODOs before merging

Merge this PR first #846

• Add tests
• Add changes to documentation (guides, repository pages, in-code descriptions)
• A changelog entry

[parse-github-assistant]

Thanks for opening this pull request!

• 🎉 We are excited about your hands-on contribution!

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (94be044) 16.36% compared to head (3128436) 16.36%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #848   +/-   ##
=======================================
  Coverage   16.36%   16.36%           
=======================================
  Files          47       47           
  Lines        2902     2902           
=======================================
  Hits          475      475           
  Misses       2427     2427           

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[parse-github-assistant]

The label type:feature cannot be used here.

[parse-github-assistant]

The label type:ci cannot be used here.

[parse-github-assistant]

The label type:ci cannot be used here.

[mtrezza]

@Nidal-Bakir just to explain the bot, most labels incl. type: can only be used on issues.

[Nidal-Bakir]

@mtrezza

[mtrezza]

Looks good!

[mtrezza]

@nidal, it seems this CI addition also fails in #846, so another fix may be needed, could you look into this?