Use MediaTransformation dims in save and load

[wd60622]

Description

Was forgotten about. Now will be used

Related Issue

• Closes #
• Related to #

Checklist

• Checked that the pre-commit linting/style checks pass. Feel free to comment pre-commit.ci autofix to auto-fix.
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks) using numpydoc format.
• If you are a pro: each commit corresponds to a relevant logical change

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📚 Documentation preview 📚: https://pymc-marketing--1503.org.readthedocs.build/en/1503/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.63%. Comparing base (6ca3a30) to head (2a64d16).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1503      +/-   ##
==========================================
+ Coverage   92.59%   92.63%   +0.03%     
==========================================
  Files          52       52              
  Lines        6051     6053       +2     
==========================================
+ Hits         5603     5607       +4     
+ Misses        448      446       -2     

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[juanitorduz]

@wd60622 can you please resolve the conflict and then feel free to merge :)

[wd60622]

pre-commit.ci autofix