Bump urllib3 from 1.25.6 to 1.25.8

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.6 to 1.25.8.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](https://github.com/urllib3/urllib3/compare/1.25.6...1.25.8)

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

requirements.txt

@@ -10,6 +10,6 @@ MarkupSafe==1.1.1
 pipreqs==0.4.9
 pkg-resources==0.0.0
 requests==2.22.0
-urllib3==1.25.6
+urllib3==1.25.8
 Werkzeug==0.16.0
 yarg==0.1.9