Bump mysqlclient from 2.2.5 to 2.2.6 (#1490)

Bumps [mysqlclient](https://github.com/PyMySQL/mysqlclient) from 2.2.5 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-patch
...

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