Replace allprojects block with subprojects block

gradle/init.gradle.kts

@@ -28,10 +28,8 @@ initscript {
     }
 }
 
-allprojects {
+rootProject {
-    if (this == rootProject) {
+    subprojects {
-        return@allprojects
-    }
         apply<com.diffplug.gradle.spotless.SpotlessPlugin>()
         extensions.configure<com.diffplug.gradle.spotless.SpotlessExtension> {
             kotlin {
@@ -54,3 +52,4 @@ allprojects {
             }
         }
     }
+}