fix: docs/requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-PILLOW-6182918

docs/requirements.txt

@@ -6,5 +6,5 @@ sphinx-autobuild
 sphinxext-opengraph
 numpy>=1.22.2 # not directly required, pinned by Snyk to avoid a vulnerability
 tornado>=6.3.3 # not directly required, pinned by Snyk to avoid a vulnerability
-pillow>=10.0.1 # not directly required, pinned by Snyk to avoid a vulnerability
+pillow>=10.2.0 # not directly required, pinned by Snyk to avoid a vulnerability
 fonttools>=4.43.0 # not directly required, pinned by Snyk to avoid a vulnerability