Add spade shape

[kunxianhuang]

Fixes #163

Describe your changes

Add spade shape

Checklist

• Test cases have been modified/added to cover any code changes.
• Docstrings have been modified/created for any code changes.
• All linting and formatting checks pass (see the contributing guidelines for more information).
• If you added a new dataset or shape, please comment on which datasets worked best for your shape or which shapes worked best for your dataset and provide the GIFs for those here.

[github-actions]

Congratulations on making your first pull request to Data Morph! Please familiarize yourself with the contributing guidelines, if you haven't already.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.47%. Comparing base (51b8d26) to head (849b16b).
Report is 25 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #225      +/-   ##
==========================================
+ Coverage   98.42%   98.47%   +0.04%     
==========================================
  Files          43       43              
  Lines        1775     1832      +57     
  Branches      358      357       -1     
==========================================
+ Hits         1747     1804      +57     
  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]

Thanks for the PR, @kunxianhuang! I pushed some changes to clean things up after working with the code from the other PR. Can you please add a test class for the spade?

You can start from what was in #195:

data-morph/tests/shapes/test_points.py

Lines 147 to 156 in 4d3ed9d

	class TestSpade(PointsModuleTestBase):
	"""Test the Spade class."""
	shape_name = 'spade'
	distance_test_cases = [
	[(20.02810385, 75.43271708), 0],
	[(29.90222827231392, 63.4652469587905), 0],
	[(19.52424889753761, 60.33944515816489), 0],
	[(20, 75), 0.2214756],
	]

[stefmolin]

Thanks for your help with this one @kunxianhuang!