Fix coverage settings to exclude tests and other minor elements

[smoia]

Closes #

Proposed Changes

Change Type

• bugfix (+0.0.1)
• minor (+0.1.0)
• major (+1.0.0)
• refactoring (no version update)
• test (no version update)
• infrastructure (no version update)
• documentation (no version update)
• other

Checklist before review

• I added everything I wanted to add to this PR.
• [Code or tests only] I wrote/updated the necessary docstrings.
• [Code or tests only] I ran and passed tests locally.
• [Documentation only] I built the docs locally.
• My contribution is harmonious with the rest of the code: I'm not introducing repetitions.
• My code respects the adopted style, especially linting conventions.
• The title of this PR is explanatory on its own, enough to be understood as part of a changelog.
• I added or indicated the right labels.

• I added information regarding the timeline of completion for this PR.

• Please, comment on my PR while it's a draft and give me feedback on the development!

[codecov]

Codecov Report

Merging #8 (02a597f) into master (fff8a17) will decrease coverage by 0.32%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #8      +/-   ##
==========================================
- Coverage   77.43%   77.10%   -0.33%     
==========================================
  Files          27       13      -14     
  Lines        1768     1057     -711     
==========================================
- Hits         1369      815     -554     
+ Misses        399      242     -157     

Impacted Files	Coverage Δ
nigsp/tests/test_laplacian.py
nigsp/tests/test_io.py
nigsp/tests/test_nifti.py
nigsp/tests/test_blocks.py
nigsp/tests/test_utils.py
nigsp/tests/test_metrics.py
nigsp/_version.py
nigsp/tests/test_timeseries.py
nigsp/tests/test_objects.py
nigsp/tests/test_viz.py
... and 4 more