Bump sphinxcontrib-bibtex from 2.6.3 to 2.6.4

Bumps [sphinxcontrib-bibtex](https://github.com/mcmtroffaes/sphinxcontrib-bibtex) from 2.6.3 to 2.6.4.
- [Changelog](https://github.com/mcmtroffaes/sphinxcontrib-bibtex/blob/develop/CHANGELOG.rst)
- [Commits](mcmtroffaes/sphinxcontrib-bibtex@2.6.3...2.6.4)

---
updated-dependencies:
- dependency-name: sphinxcontrib-bibtex
  dependency-version: 2.6.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/requirements.txt

@@ -1,6 +1,6 @@
 sphinx==8.2.3
 sphinx-rtd-theme==3.0.2
-sphinxcontrib-bibtex==2.6.3
+sphinxcontrib-bibtex==2.6.4
 setuptools==80.9.0
 myst_parser==4.0.1
 sphinx_subfigure==0.2.4