feat(CI): #50 fix CI workflow

[rohaquinlop]

• Fix CI workflow errors.
• Change the runs-on to ubuntu-latest for sdist job.
• Split the pytest job into a new unit-tests job.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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