fix: docs/requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-SETUPTOOLS-9964606

Author: snyk-bot

docs/requirements.txt

@@ -6,7 +6,7 @@ markupsafe==2.0.1
 pydata-sphinx-theme==0.7.2
 pygments>=2.15.0 # not directly required, pinned by Snyk to avoid a vulnerability
 requests>=2.32.2 # not directly required, pinned by Snyk to avoid a vulnerability
-setuptools>=70.0.0 # not directly required, pinned by Snyk to avoid a vulnerability
+setuptools>=78.1.1 # not directly required, pinned by Snyk to avoid a vulnerability
 sphinx==4.3.0
 sphinx-autoapi==1.8.4
 sphinx-code-include==1.1.1