Bump urllib3 from 1.25.3 to 1.25.9

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.3 to 1.25.9.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/master/CHANGES.rst)
- [Commits](urllib3/urllib3@1.25.3...1.25.9)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -10,4 +10,4 @@ chardet==3.0.4            # via requests
 idna==2.8                 # via requests
 requests==2.22.0
 six==1.12.0
-urllib3==1.25.3           # via requests
+urllib3==1.25.9           # via requests