Remove upper limit restriction on pandas

[nfahlgren]

Describe your changes
Removes limit on the maximum version of pandas supported. Fixes issue with tests for constella that used a deprecated pandas DataFrame method.

Type of update
Is this a: update

For the reviewer
See this page for instructions on how to review the pull request.

• 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 #1354 (c446d43) into main (e1e3a46) will not change coverage.
Report is 2 commits behind head on main.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main     #1354   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          155       155           
  Lines         6840      6840           
=========================================
  Hits          6840      6840           

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

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

[nfahlgren]

These changes were accidentally pushed to main, so closing.