fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-MKDOCSMATERIAL-7856160

requirements.txt

@@ -69,7 +69,7 @@ mkdocs-autorefs==0.4.1
     # via mkdocstrings
 mkdocs-click==0.5.0
     # via -r requirements.in
-mkdocs-material==8.2.5
+mkdocs-material==9.5.32
     # via -r requirements.in
 mkdocs-material-extensions==1.0.3
     # via mkdocs-material