fix: add target java version to avoid compile error (#37)

Author: bdlukaa

system_theme/android/build.gradle

@@ -27,7 +27,14 @@ apply plugin: 'kotlin-android'
 android {
     namespace 'com.bruno.system_theme'
     compileSdkVersion 31
-
+    
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_1_8
+    }
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
     }