Bump jinja2 from 2.11.3 to 3.1.6 in /docs

Bumps [jinja2](https://github.com/pallets/jinja) from 2.11.3 to 3.1.6.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/main/CHANGES.rst)
- [Commits](pallets/jinja@2.11.3...3.1.6)

---
updated-dependencies:
- dependency-name: jinja2
  dependency-version: 3.1.6
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/rtd-requirements.txt

@@ -4,7 +4,7 @@ Babel==2.9.1
 DateTime==3.0.3
 DocumentTemplate==2.13.2
 ExtensionClass==2.13.2
-Jinja2==2.11.3
+Jinja2==3.1.6
 Markdown==2.0.3
 MarkupSafe==0.23
 Missing==2.13.1