Bump jinja2 from 3.1.5 to 3.1.6 in /docs (#1722)

Bumps [jinja2](https://github.com/pallets/jinja) from 3.1.5 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@3.1.5...3.1.6)

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -9,7 +9,7 @@ docutils==0.15.2
 exhale==0.2.4
 idna==3.7
 imagesize==1.1.0
-Jinja2==3.1.5
+Jinja2==3.1.6
 lxml==4.9.1
 MarkupSafe==2.1.3
 packaging==19.2