[BUG] The generator creates a 'kotlin-server' project that uses the old Ktor version

Created by: andreyaksenov

The command below generates a new Ktor project from the documentation.yaml spec:

openapi-generator generate -g kotlin-server -i documentation.yaml -o /tmp/openapi/kotlin-server/

The resulting project uses an old Ktor version (1.5.4), while the current version is 2.1.3. The project also uses the Locations plugin (AppMain.kt) that can be replaced with a new Resources plugin.