chore(deps): bump com.zaxxer:HikariCP from 6.1.0 to 6.2.1 in /backend

Bumps [com.zaxxer:HikariCP](https://github.com/brettwooldridge/HikariCP) from 6.1.0 to 6.2.1.
- [Changelog](https://github.com/brettwooldridge/HikariCP/blob/dev/CHANGES)
- [Commits](brettwooldridge/HikariCP@HikariCP-6.1.0...HikariCP-6.2.1)

---
updated-dependencies:
- dependency-name: com.zaxxer:HikariCP
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/build.gradle

@@ -140,7 +140,7 @@ subprojects {
         implementation("org.jetbrains.exposed:exposed-dao:0.39.2")
         implementation("org.jetbrains.exposed:exposed-jdbc:0.39.2")
 
-        implementation 'com.zaxxer:HikariCP:6.1.0'
+        implementation 'com.zaxxer:HikariCP:6.2.1'
 
         //JDBC Drivers
         implementation 'org.xerial:sqlite-jdbc:3.47.0.0'