Update installation.md

[HaleySchuhl]

Describe your changes
Update to docs describing dependencies required

Type of update
Is this a:

• Update to documentation

Associated issues

• closes Installation dependencies in docs aren't up to date #976

Additional context
Add any other context about the problem here.

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 #977 (4a0195e) into main (7cc666e) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #977   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          129       129           
  Lines         5813      5813           
=========================================
  Hits          5813      5813           

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

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

[nfahlgren]

Thanks!