upgrade gecko. gradle, deps

packages/flutter_singbox_proxy/example/android/app/build.gradle

@@ -1,12 +1,11 @@
 plugins {
     id "com.android.application"
-    id "kotlin-android"
     id "dev.flutter.flutter-gradle-plugin"
 }
 
 android {
     namespace = "eu.weblibre.flutter_singbox_proxy_example"
-    compileSdk = flutter.compileSdkVersion
+    compileSdk = 37
     ndkVersion = flutter.ndkVersion
 
     compileOptions {
@@ -14,10 +13,6 @@ android {
         targetCompatibility = JavaVersion.VERSION_17
     }
 
-    kotlinOptions {
-        jvmTarget = JavaVersion.VERSION_17
-    }
-
     defaultConfig {
         applicationId = "eu.weblibre.flutter_singbox_proxy_example"
         minSdk = flutter.minSdkVersion
@@ -33,6 +28,12 @@ android {
     }
 }
 
+kotlin {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+    }
+}
+
 flutter {
     source = "../.."
 }