Bump pymysql from 0.9.3 to 0.10.0 in /backend

Bumps [pymysql](https://github.com/PyMySQL/PyMySQL) from 0.9.3 to 0.10.0.
- [Release notes](https://github.com/PyMySQL/PyMySQL/releases)
- [Changelog](https://github.com/PyMySQL/PyMySQL/blob/master/CHANGELOG.md)
- [Commits](https://github.com/PyMySQL/PyMySQL/commits)

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

Author: dependabot[bot]

backend/requirements.txt

@@ -8,7 +8,7 @@ python-dotenv==0.13.0
 Geohash==1.0
 python-geohash==0.8.5
 
-pymysql==0.9.3
+pymysql==0.10.0
 
 Flask-Mail==0.9.1