Bump mysqlclient from 2.1.1 to 2.2.6

Bumps [mysqlclient](https://github.com/PyMySQL/mysqlclient) from 2.1.1 to 2.2.6.
- [Release notes](https://github.com/PyMySQL/mysqlclient/releases)
- [Changelog](https://github.com/PyMySQL/mysqlclient/blob/main/HISTORY.rst)
- [Commits](https://github.com/PyMySQL/mysqlclient/commits)

---
updated-dependencies:
- dependency-name: mysqlclient
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements/wmf.txt

@@ -1,4 +1,4 @@
 -r base.txt
 -r test.txt
 gunicorn==23.0.0
-mysqlclient==2.1.1
+mysqlclient==2.2.6