[ci] Remove the unit tests from the coverage report

[teojgo]

Fixes #1516

[codecov-io]

Codecov Report

Merging #1518 into master will decrease coverage by 3.64%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1518      +/-   ##
==========================================
- Coverage   91.55%   87.90%   -3.65%     
==========================================
  Files          83       43      -40     
  Lines       13223     6839    -6384     
==========================================
- Hits        12106     6012    -6094     
+ Misses       1117      827     -290     

Impacted Files	Coverage Δ
...s/resources/checks_unlisted/no_required_version.py
unittests/resources/checks/hellocheck.py
unittests/test_policies.py
unittests/test_argparser.py
...tests/resources/checks_unlisted/deprecated_test.py
unittests/test_shell.py
unittests/test_launchers.py
unittests/test_utility.py
...ittests/resources/checks_unlisted/kbd_interrupt.py
unittests/test_cli.py
... and 30 more

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[vkarak]

lgtm