fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-H11-10293728

Author: snyk-bot

requirements.txt

@@ -24,3 +24,4 @@ pillow>=10.3.0 # not directly required, pinned by Snyk to avoid a vulnerability
 setuptools>=78.1.1 # not directly required, pinned by Snyk to avoid a vulnerability
 fonttools>=4.43.0 # not directly required, pinned by Snyk to avoid a vulnerability
 zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability
+h11>=0.16.0 # not directly required, pinned by Snyk to avoid a vulnerability