Bump plugin.serialization from 1.9.10 to 1.9.20 in /whiskers-ktor-no-db

Bumps [plugin.serialization](https://github.com/JetBrains/kotlin) from 1.9.10 to 1.9.20.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/commits)

---
updated-dependencies:
- dependency-name: plugin.serialization
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

whiskers-ktor-no-db/build.gradle.kts

@@ -1,7 +1,7 @@
 plugins {
     application
     kotlin("multiplatform") version "1.9.10"
-    kotlin("plugin.serialization") version "1.9.10"
+    kotlin("plugin.serialization") version "1.9.20"
 }
 
 group = "org.jesperancinha.native"