build(deps): bump sphinx-gallery from 0.15.0 to 0.16.0 in /requirements

Bumps [sphinx-gallery](https://github.com/sphinx-gallery/sphinx-gallery) from 0.15.0 to 0.16.0.
- [Release notes](https://github.com/sphinx-gallery/sphinx-gallery/releases)
- [Changelog](https://github.com/sphinx-gallery/sphinx-gallery/blob/master/.github_changelog_generator)
- [Commits](sphinx-gallery/sphinx-gallery@v0.15.0...v0.16.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements/requirements_doc.txt

@@ -16,7 +16,7 @@ sphinx-copybutton==0.5.2
 jupyter_sphinx==0.5.3
 jupyterlab>=3.2.8
 sphinxemoji==0.3.1
-sphinx-gallery==0.15.0
+sphinx-gallery==0.16.0
 sphinx-autobuild==2024.2.4
 sphinx-autodoc-typehints==2.0.0
 sphinx-design==0.5.0