fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-JINJA2-6150717
- https://snyk.io/vuln/SNYK-PYTHON-JINJA2-6809379
- https://snyk.io/vuln/SNYK-PYTHON-MKDOCS-1729735
- https://snyk.io/vuln/SNYK-PYTHON-MKDOCS-2438396
- https://snyk.io/vuln/SNYK-PYTHON-SETUPTOOLS-3180412
- https://snyk.io/vuln/SNYK-PYTHON-SETUPTOOLS-7448482
- https://snyk.io/vuln/SNYK-PYTHON-TORNADO-5537286
- https://snyk.io/vuln/SNYK-PYTHON-TORNADO-5840803
- https://snyk.io/vuln/SNYK-PYTHON-TORNADO-6041512
- https://snyk.io/vuln/SNYK-PYTHON-TORNADO-7217828
- https://snyk.io/vuln/SNYK-PYTHON-TORNADO-7217829

requirements.txt

@@ -8,3 +8,6 @@ mkdocs-git-revision-date-localized-plugin==1.1.0
 mkdocs-macros-plugin==0.7.0
 mkdocs-with-pdf==0.9.3
 zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability
+jinja2>=3.1.4 # not directly required, pinned by Snyk to avoid a vulnerability
+setuptools>=70.0.0 # not directly required, pinned by Snyk to avoid a vulnerability
+tornado>=6.4.1 # not directly required, pinned by Snyk to avoid a vulnerability