Fix laplacian and degree shape check in laplacian.normalisation

[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 #82 (04fd91c) into master (7a24212) will decrease coverage by 0.08%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master      #82      +/-   ##
==========================================
- Coverage   90.93%   90.85%   -0.08%     
==========================================
  Files          14       14              
  Lines        1235     1236       +1     
==========================================
  Hits         1123     1123              
- Misses        112      113       +1     

Files	Coverage Δ
nigsp/operations/laplacian.py	95.78% <100.00%> (ø)
nigsp/workflow.py	74.43% <0.00%> (-0.34%)	⬇️

[smoia]

🚀 PR was released in 0.18.3 🚀