build(deps): bump requests from 2.15.1 to 2.20.0 in /docs

Bumps [requests](https://github.com/psf/requests) from 2.15.1 to 2.20.0.
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.15.1...v2.20.0)

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

docs/requirements.txt

@@ -52,7 +52,7 @@ pytest==6.2.2; python_version >= "3.6"
 pytz==2021.1; python_version >= "3.5" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.5"
 pyyaml==5.4.1; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.6.0" and python_version >= "3.6"
 regex==2021.3.17; python_version >= "3.6"
-requests==2.15.1; python_version >= "3.5"
+requests==2.20.0; python_version >= "3.5"
 six==1.15.0; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0"
 snowballstemmer==2.1.0; python_version >= "3.6"
 soupsieve==2.2.1; python_full_version >= "3.6.1" and python_full_version < "4.0.0" and python_version >= "3.6"