chore(node): Prefer Kotlin's in operator over contains()

Signed-off-by: Sebastian Schuberth <[email protected]>

plugins/package-managers/node/src/main/kotlin/Yarn2.kt

@@ -151,7 +151,7 @@ class Yarn2(
          */
         private fun isCorepackEnabledInManifest(workingDir: File): Boolean =
             runCatching {
-                jsonMapper.readTree(workingDir.resolve(MANIFEST_FILE)).contains(PACKAGE_MANAGER_PROPERTY)
+                PACKAGE_MANAGER_PROPERTY in jsonMapper.readTree(workingDir.resolve(MANIFEST_FILE))
             }.getOrDefault(false)
     }