Add missing highlighting for Python snippets

[aslisabanci]

What does this PR do?

Adds missing highlighting for Python for example and test code snippets. Can continue with similar fixes for the remaining doc pages if this PR looks okay.

Does your PR introduce any breaking changes ? If yes, please list them.

No.

Before submitting

• [N/A] Was this discussed/approved via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• [N/A] Did you make sure to update the documentation with your changes? (if necessary)
• [N/A] Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• [N/A] Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)
• Did you list all the breaking changes introduced by this pull request?

PR review

Anyone in the community is free to review the PR once the tests have passed.
Before you start reviewing make sure you have read Review guidelines. In short, see the following bullet-list:

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
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Did you have fun?

YES, excited for the 1st PR!🙃

[codecov]

Codecov Report

Merging #8411 (fbec9a5) into master (74a09a2) will decrease coverage by 4%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #8411    +/-   ##
=======================================
- Coverage      92%     88%    -4%     
=======================================
  Files         216     218     +2     
  Lines       14112   14405   +293     
=======================================
- Hits        13017   12705   -312     
- Misses       1095    1700   +605     

[awaelchli]

thanks for the help here @aslisabanci <3