fix: requirements-docs.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-PYGMENTS-5750273
- https://snyk.io/vuln/SNYK-PYTHON-SPHINX-570772
- https://snyk.io/vuln/SNYK-PYTHON-SPHINX-570773
- https://snyk.io/vuln/SNYK-PYTHON-SPHINX-5811865
- https://snyk.io/vuln/SNYK-PYTHON-SPHINX-5812109

requirements-docs.txt

@@ -1,16 +1,16 @@
 # Newer versions of Jinja break our current copy of Sphinx
 # See https://github.com/sphinx-doc/sphinx/issues/10306 for details
-jinja2<3.1
+jinja2<3.1.4
 
 
 docutils>=0.10,<0.17
-Sphinx==1.4.9
+Sphinx==3.3.0
 -e .
 # alabaster version 0.7.13 requires Sphinx>1.6
 alabaster>0.7,<0.7.13
 # Required by Sphinx==1.3.2. (TODO: remove these when upgrading sphinx)
 babel<=2.11.0 # via sphinx
-pygments<=2.14.0 # via sphinx
+pygments<=2.15.0 # via sphinx
 pytz<=2022.7 # via babel
 snowballstemmer<=2.2.0 # via sphinx
 sphinx-rtd-theme<=0.5.2 # via sphinx