Bump mysqlclient from 2.2.3 to 2.2.4

Bumps [mysqlclient](https://github.com/PyMySQL/mysqlclient) from 2.2.3 to 2.2.4.
- [Release notes](https://github.com/PyMySQL/mysqlclient/releases)
- [Changelog](https://github.com/PyMySQL/mysqlclient/blob/main/HISTORY.rst)
- [Commits](PyMySQL/mysqlclient@v2.2.3...v2.2.4)

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

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

requirements/mariadb.txt

@@ -1,2 +1,2 @@
 -r base.txt
-mysqlclient==2.2.3
+mysqlclient==2.2.4