chore(deps): bump com.mysql:mysql-connector-j in /backend

Bumps [com.mysql:mysql-connector-j](https://github.com/mysql/mysql-connector-j) from 9.0.0 to 9.1.0.
- [Changelog](https://github.com/mysql/mysql-connector-j/blob/release/9.x/CHANGES)
- [Commits](mysql/mysql-connector-j@9.0.0...9.1.0)

---
updated-dependencies:
- dependency-name: com.mysql:mysql-connector-j
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

backend/pom.xml

@@ -60,7 +60,7 @@
         <dependency>
             <groupId>com.mysql</groupId>
             <artifactId>mysql-connector-j</artifactId>
-            <version>9.0.0</version>
+            <version>9.1.0</version>
         </dependency>
         <dependency>
             <groupId>org.liquibase</groupId>