Bump sphinx-thebe from 0.2.1 to 0.3.1

Bumps [sphinx-thebe](https://github.com/executablebooks/sphinx-thebe) from 0.2.1 to 0.3.1.
- [Release notes](https://github.com/executablebooks/sphinx-thebe/releases)
- [Changelog](https://github.com/executablebooks/sphinx-thebe/blob/main/CHANGELOG.md)
- [Commits](executablebooks/sphinx-thebe@v0.2.1...v0.3.1)

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -11,7 +11,7 @@ sphinx-version-warning==1.1.2
 sphinx-book-theme==1.0.1
 sphinx-external-toc>=0.3.0
 sphinx-inline-tabs
-sphinx-thebe==0.2.1
+sphinx-thebe==0.3.1
 sphinx-remove-toctrees==0.0.3
 sphinx_design==0.5.0
 sphinx_multiversion>=0.2.4