Bump Flutter (v3.19) and dependencies

android/app/build.gradle

@@ -1,3 +1,9 @@
+plugins {
+    id "com.android.application"
+    id "kotlin-android"
+    id "dev.flutter.flutter-gradle-plugin"
+}
+
 def localProperties = new Properties()
 def localPropertiesFile = rootProject.file('local.properties')
 if (localPropertiesFile.exists()) {
@@ -6,11 +12,6 @@ if (localPropertiesFile.exists()) {
     }
 }
 
-def flutterRoot = localProperties.getProperty('flutter.sdk')
-if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
-}
-
 boolean hasKeyStore = false
 
 def keystoreProperties = new Properties()
@@ -39,10 +40,6 @@ if (flutterVersionName == null) {
     flutterVersionName = '1.0'
 }
 
-apply plugin: 'com.android.application'
-apply plugin: 'kotlin-android'
-apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
-
 android {
     namespace "com.hiddify.hiddify"
     compileSdkVersion 34
@@ -127,7 +124,6 @@ flutter {
 dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar', '*.aar'])
     implementation 'com.google.code.gson:gson:2.10.1'
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     implementation 'androidx.core:core-ktx:1.12.0'
     implementation 'androidx.appcompat:appcompat:1.6.1'
     implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.6.2'