Scipy ndimage namespace fix

[joshqsumner]

Describe your changes
Changed the namespace for two functions being imported ( scipy.ndimage.morphology -> scipy.ndimage , and scipy.ndimage.filters -> scipy.ndimage) in fill_holes.py and median_blur.py.

Type of update
Is this a:

• Bug fix (fixing a deprecation warning)

Associated issues
See comments in #999

Additional context
None

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 #1025 (d9dbcb1) into main (7f170eb) will not change coverage.
The diff coverage is 100.00%.

❗ Current head d9dbcb1 differs from pull request most recent head 6f7b7ba. Consider uploading reports for the commit 6f7b7ba to get more accurate results

@@           Coverage Diff           @@
##             main    #1025   +/-   ##
=======================================
  Coverage   99.98%   99.98%           
=======================================
  Files         141      141           
  Lines        6004     6004           
=======================================
  Hits         6003     6003           
  Misses          1        1           

Flag	Coverage Δ
unittests	99.98% <100.00%> (ø)

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

Impacted Files	Coverage Δ
plantcv/plantcv/fill_holes.py	100.00% <100.00%> (ø)
plantcv/plantcv/median_blur.py	100.00% <100.00%> (ø)