⬆️ Bump urllib3 from 1.26.18 to 1.26.19 in /requirements

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](urllib3/urllib3@1.26.18...1.26.19)

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

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

Author: dependabot[bot]

requirements/constraints.txt

@@ -55,7 +55,7 @@ towncrier==21.3.0         # via -r requirements/dev.in
 tox==3.24.5               # via -r requirements/ci.in
 tqdm==4.66.3              # via twine
 twine==3.7.1              # via -r requirements/dev.in
-urllib3==1.26.18           # via requests
+urllib3==1.26.19           # via requests
 virtualenv==20.13.0       # via pre-commit, tox
 webencodings==0.5.1       # via bleach
 werkzeug==2.0.2           # via -r requirements/tests.in