Add spade shape

[kevinr1299]

Fixes #163

Describe your changes

Add the logic to morph into a spade shape

Checklist

• [X] Test cases have been modified/added to cover any code changes.
• [X] Docstrings have been modified/created for any code changes.
• [X] All linting and formatting checks pass (see the contributing guidelines for more information).

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.43%. Comparing base (51b8d26) to head (4d3ed9d). Report is 25 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #195      +/-   ##
==========================================
+ Coverage   98.42%   98.43%   +0.01%     
==========================================
  Files          43       43              
  Lines        1775     1792      +17     
  Branches      358      360       +2     
==========================================
+ Hits         1747     1764      +17     
  Misses         25       25              
  Partials        3        3              

Files with missing lines	Coverage Δ
src/data_morph/shapes/factory.py	100.00% <ø> (ø)
src/data_morph/shapes/points.py	100.00% <100.00%> (ø)
tests/shapes/test_points.py	100.00% <100.00%> (ø)

[stefmolin]

This was completed in #225.