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

@@ -1,5 +1,5 @@
 mkdocs==1.4.2
-mkdocs-material==9.0.2
+mkdocs-material==9.5.32
 mkdocs-material-extensions==1.1.1
 mkdocs-minify-plugin==0.6.2
 mike==1.1.2