Bump urllib3 from 1.21.1 to 1.24.2

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.21.1 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@1.21.1...1.24.2)

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

requirements.txt

@@ -18,7 +18,7 @@ requests==2.9.1
 requests-oauthlib==0.6.1
 scutils==1.3.0dev2
 tenacity>=4.0.1,<=4.3
-urllib3==1.21.1
+urllib3==1.24.2
 uwsgi==2.0.15
 pykafka==2.6.0
 gevent==1.2.2