⬆️ Bump org.jetbrains.kotlin:kotlin-reflect in /backend

Bumps [org.jetbrains.kotlin:kotlin-reflect](https://github.com/JetBrains/kotlin) from 2.0.21 to 2.1.0.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.1.0)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-reflect
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/build.gradle.kts

@@ -32,7 +32,7 @@ dependencies {
     testImplementation("org.springframework.boot:spring-boot-starter-test")
     testImplementation("org.springframework.security:spring-security-test")
 
-    implementation("org.jetbrains.kotlin:kotlin-reflect:2.0.21")
+    implementation("org.jetbrains.kotlin:kotlin-reflect:2.1.0")
     implementation("com.fasterxml.jackson.module:jackson-module-kotlin:2.18.2")
     implementation("org.flywaydb:flyway-core:11.0.0")
     implementation("org.flywaydb:flyway-database-postgresql:11.0.0")