Refactor: Use placeholders for Compose dependencies in test

Updated the `macLayeredIcon` test project to use `COMPOSE_VERSION_PLACEHOLDER` for Compose dependency versions. This makes the test configuration more flexible and easier to maintain.

Author: Sanlorng

gradle-plugins/compose/src/test/test-projects/application/macLayeredIcon/build.gradle.kts

@@ -33,8 +33,8 @@ kotlin {
     sourceSets {
         commonMain {
             dependencies {
-                implementation(compose.runtime)
-                implementation(compose.material)
+                implementation("org.jetbrains.compose.runtime:runtime:COMPOSE_VERSION_PLACEHOLDER")
+                implementation("org.jetbrains.compose.material:material:COMPOSE_VERSION_PLACEHOLDER")
             }
         }