Bump urllib3 from 1.26.18 to 1.26.19

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.18 to 1.26.19.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/1.26.19/CHANGES.rst)
- [Commits](https://github.com/urllib3/urllib3/compare/1.26.18...1.26.19)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
...

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

requirements.txt

@@ -16,4 +16,4 @@ pytz==2021.1
 six==1.16.0
 tornado==6.3.3
 tzlocal==2.1
-urllib3==1.26.18
+urllib3==1.26.19