chore(deps): bump org.flywaydb:flyway-core from 11.4.1 to 11.15.0

Bumps [org.flywaydb:flyway-core](https://github.com/flyway/flyway) from 11.4.1 to 11.15.0.
- [Release notes](https://github.com/flyway/flyway/releases)
- [Commits](flyway/flyway@flyway-11.4.1...flyway-11.15.0)

---
updated-dependencies:
- dependency-name: org.flywaydb:flyway-core
  dependency-version: 11.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

build.gradle.kts

@@ -49,8 +49,8 @@ repositories {
 dependencies {
     implementation("org.springframework.boot:spring-boot-starter-data-jpa")
     runtimeOnly("org.postgresql:postgresql")
-    implementation("org.flywaydb:flyway-core:11.4.1") // TODO: remove explicit version when the Spring Boot version is updated
-    implementation("org.flywaydb:flyway-database-postgresql:11.4.1")
+    implementation("org.flywaydb:flyway-core:11.15.0") // TODO: remove explicit version when the Spring Boot version is updated
+    implementation("org.flywaydb:flyway-database-postgresql:11.15.0")
 
     implementation("org.springframework.boot:spring-boot-starter-mail")