Pin theme dependencies and ignore generated docs

[timkpaine]

sphinx-fuma and sphinx-searchlite were added unpinned, so a resolver could pick sphinx-searchlite 0.1.0, which lacks the host-theme colour and search box adoption yardang relies on.

Also ignore the wiki doctrees and jupyter_execute output, which a docs build otherwise leaves behind as if they were source, and drop the duplicate sphinx-fuma entry in develop that the core dependency already covers.

Description

Brief description of the changes in this PR.

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup
• CI / build configuration
• Other (describe below)

Checklist

• Linting passes (make lint)
• Tests pass (make test)
• New tests added for new functionality
• Documentation updated (if applicable)
• Changelog / version bump (if applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.48%. Comparing base (74e40c9) to head (e722be1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #149      +/-   ##
==========================================
- Coverage   85.53%   85.48%   -0.06%     
==========================================
  Files          15       15              
  Lines        1936     1936              
  Branches      204      204              
==========================================
- Hits         1656     1655       -1     
  Misses        216      216              
- Partials       64       65       +1     

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