Bump urllib3 from 1.26.2 to 1.26.4

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.2 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/1.26.2...1.26.4)

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

requirements.txt

@@ -52,7 +52,7 @@ speaklater==1.3
 SQLAlchemy==1.3.20
 SQLAlchemy-Utils==0.36.8
 Unidecode==1.1.1
-urllib3==1.26.2
+urllib3==1.26.4
 vine==5.0.0
 Werkzeug==1.0.1
 Whoosh==2.7.4