[Tech] Bump org.flywaydb:flyway-core from 10.21.0 to 11.0.0 in /backend

Bumps [org.flywaydb:flyway-core](https://github.com/flyway/flyway) from 10.21.0 to 11.0.0.
- [Release notes](https://github.com/flyway/flyway/releases)
- [Commits](flyway/flyway@flyway-10.21.0...flyway-11.0.0)

---
updated-dependencies:
- dependency-name: org.flywaydb:flyway-core
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

backend/build.gradle.kts

@@ -54,7 +54,7 @@ dependencies {
     implementation("com.fasterxml.jackson.module:jackson-module-kotlin:2.18.1")
     implementation("org.n52.jackson:jackson-datatype-jts:1.2.10")
     implementation("com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0")
-    implementation("org.flywaydb:flyway-core:10.21.0")
+    implementation("org.flywaydb:flyway-core:11.0.0")
     implementation("org.flywaydb:flyway-database-postgresql:10.21.0")
     implementation("org.jetbrains.kotlin:kotlin-reflect:2.0.21")
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8:2.0.21")