Bump urllib3 from 1.25.3 to 1.25.8

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.3 to 1.25.8.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.25.3...1.25.8)

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

Author: dependabot[bot]

requirements.txt

@@ -14,4 +14,4 @@ pytz==2019.2
 requests==2.22.0
 sqlparse==0.3.0
 uritemplate==3.0.0
-urllib3==1.25.3
+urllib3==1.25.8