Bump sphinx-gallery from 0.19.0 to 0.20.0 (#68)

Bumps [sphinx-gallery](https://github.com/sphinx-gallery/sphinx-gallery) from 0.19.0 to 0.20.0.
- [Release notes](https://github.com/sphinx-gallery/sphinx-gallery/releases)
- [Changelog](https://github.com/sphinx-gallery/sphinx-gallery/blob/master/CHANGES.rst)
- [Commits](sphinx-gallery/sphinx-gallery@v0.19.0...v0.20.0)

---
updated-dependencies:
- dependency-name: sphinx-gallery
  dependency-version: 0.20.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

documentation-requirements.txt

@@ -2,7 +2,7 @@ autodocsumm==0.2.14
 myst_parser==4.0.1
 sphinx
 sphinx-autodoc-typehints==3.6.2
-sphinx-gallery==0.19.0
+sphinx-gallery==0.20.0
 sphinx-jinja2-compat==0.4.1
 sphinx-prompt==1.10.2
 sphinx-rtd-theme==3.0.2