build(deps): bump urllib3 from 1.24.1 to 1.24.2 in /requirements

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.24.1 to 1.24.2.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/master/CHANGES.rst)
- [Commits](urllib3/urllib3@1.24.1...1.24.2)

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

requirements/docs.txt

@@ -26,6 +26,5 @@ sphinx-argparse==0.2.5
 sphinx-intl==0.9.11
 sphinx==1.8.5
 sphinxcontrib-websupport==1.1.0  # via sphinx
-typing==3.6.6             # via sphinx
-urllib3==1.24.1           # via requests
+urllib3==1.24.2           # via requests
 zope.interface==4.6.0     # via repoze.sphinx.autointerface