Deprecate visualize cluster contours

[HaleySchuhl]

Describe your changes

Type of update
Is this a:

• Update

Associated issues
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Additional context
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• PR functionality reviewed in a Jupyter Notebook
• All tests pass
• Test coverage remains 100%
• Documentation tested
• New documentation pages added to plantcv/mkdocs.yml
• Changes to function input/output signatures added to updating.md
• Code reviewed
• PR approved

[codecov]

Codecov Report

Merging #1229 (2a4793c) into release-4.0 (d060dff) will not change coverage.
The diff coverage is 100.00%.

@@              Coverage Diff              @@
##           release-4.0     #1229   +/-   ##
=============================================
  Coverage       100.00%   100.00%           
=============================================
  Files              161       160    -1     
  Lines             6954      6919   -35     
=============================================
- Hits              6954      6919   -35     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
plantcv/plantcv/visualize/__init__.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes