build(deps): bump pytz from 2021.1 to 2023.3 in /docs (#2520)

Bumps [pytz](https://github.com/stub42/pytz) from 2021.1 to 2023.3.
- [Commits](stub42/pytz@release_2021.1...release_2023.3)

---
updated-dependencies:
- dependency-name: pytz
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/requirements.txt

@@ -11,7 +11,7 @@ MarkupSafe==2.1.3
 packaging==23.1
 Pygments==2.15.1
 pyparsing==2.4.7
-pytz==2021.1
+pytz==2023.3
 recommonmark==0.7.1
 requests==2.31.0
 snowballstemmer==2.2.0