Add Gitlab CI to Coverage

[theogf]

This allows to directly submit the Coverage report to Codecov or Coveralls from a Gitlab action.
This solves #330

[coveralls]

Pull Request Test Coverage Report for Build 2378694128

• 13 of 13 (100.0%) changed or added relevant lines in 2 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+1.06%) to 91.441%

---

Files with Coverage Reduction	New Missed Lines	%
src/codecovio.jl	2	87.96%
src/coveralls.jl	2	94.74%

Totals
Change from base Build 1363428186:	1.06%
Covered Lines:	203
Relevant Lines:	222

---

💛 - Coveralls

[codecov]

Codecov Report

Merging #331 (dfeda28) into master (e22e4fe) will increase coverage by 1.34%.
The diff coverage is 100.00%.

❗ Current head dfeda28 differs from pull request most recent head 0f0258d. Consider uploading reports for the commit 0f0258d to get more accurate results

@@            Coverage Diff             @@
##           master     #331      +/-   ##
==========================================
+ Coverage   90.09%   91.44%   +1.34%     
==========================================
  Files           2        2              
  Lines         212      222      +10     
==========================================
+ Hits          191      203      +12     
+ Misses         21       19       -2     

Impacted Files	Coverage Δ
src/codecovio.jl	87.96% <100.00%> (+3.85%)	⬆️
src/coveralls.jl	94.73% <100.00%> (-1.46%)	⬇️

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[maleadt]

There's tests for the other providers, so this PR better needs some as well.

[theogf]

Sorry I realized some of the tags were wrong, but somehow I could not change it to draft mode.
Right now push on main works fine but push on a merge request fails.
You can see the results on this test package : https://gitlab.com/theogf/testpackage.jl/-/tree/main

[maleadt]

OK, I've moved it back to draft.

[theogf]

Ok sorry for the whole CI mess! Testing this kind of stuff is really painful! I can now confirm it works for both push on master/main and merge requests (Gitlab name for PRs)

[theogf]

It should now be ready for merging. As said above you can check how it looks on https://gitlab.com/theogf/testpackage.jl/-/tree/main

[theogf]

Not sure about the bump on the Project.toml, should it be 1.5.0 or 1.4.1 ?

[maleadt]

Since this is a new features, 1.5.0 would be best.