Bump urllib3 from 1.26.3 to 1.26.4 (#90)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.3 to 1.26.4.
- [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/1.26.3...1.26.4)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements-travis.txt

@@ -59,7 +59,7 @@ six==1.14.0
 tabulate==0.8.7
 testinfra==6.0.0
 tree-format==0.1.2
-urllib3==1.26.3
+urllib3==1.26.4
 websocket-client==0.57.0
 whichcraft==0.6.1
 yamllint==1.26.0