Bump jinja2 from 2.10.1 to 2.11.3 in /docs

Bumps [jinja2](https://github.com/pallets/jinja) from 2.10.1 to 2.11.3.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/master/CHANGES.rst)
- [Commits](pallets/jinja@2.10.1...2.11.3)

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

docs/requirements.txt

@@ -26,7 +26,7 @@ ipyvolume==0.5.1
 ipywebrtc==0.4.3
 ipywidgets==7.4.2
 jedi==0.13.3
-jinja2==2.10.1
+jinja2==2.11.3
 jsonschema==3.0.1
 jupyter-client==5.2.4
 jupyter-core==4.4.0