[Tech] Bump org.jetbrains.kotlin.plugin.allopen in /backend

Bumps [org.jetbrains.kotlin.plugin.allopen](https://github.com/JetBrains/kotlin) from 1.9.10 to 1.9.22.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.10...v1.9.22)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin.plugin.allopen
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

backend/build.gradle.kts

@@ -4,7 +4,7 @@ plugins {
     id("org.springframework.boot") version "3.1.7"
     id("org.jetbrains.kotlin.plugin.spring") version "1.9.10"
     kotlin("jvm") version "1.9.22"
-    id("org.jetbrains.kotlin.plugin.allopen") version "1.9.10"
+    id("org.jetbrains.kotlin.plugin.allopen") version "1.9.22"
     kotlin("plugin.noarg") version "1.9.10"
     kotlin("plugin.jpa") version "1.9.22"
     id("org.jlleitschuh.gradle.ktlint") version "11.6.1"