Update/fix android configuration

It seems some packages that have not been updated in some years are causing
problems. android_metadata has been removed here, but flutter_barcode_scanner
is still needed

android/app/build.gradle

@@ -12,16 +12,6 @@ if (localPropertiesFile.exists()) {
     }
 }
 
-def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
-if (flutterVersionCode == null) {
-    flutterVersionCode = '1'
-}
-
-def flutterVersionName = localProperties.getProperty('flutter.versionName')
-if (flutterVersionName == null) {
-    flutterVersionName = '1.0'
-}
-
 
 // Keys for the android play store
 def keystoreProperties = new Properties()
@@ -32,33 +22,27 @@ if (keystorePropertiesFile.exists()) {
 
 
 android {
+    namespace = "de.wger.flutter"
     compileSdkVersion 34
     ndkVersion "25.1.8937393"
 
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_17
-        targetCompatibility JavaVersion.VERSION_17
+        sourceCompatibility JavaVersion.VERSION_11
+        targetCompatibility JavaVersion.VERSION_11
     }
 
     kotlinOptions {
-        jvmTarget = '1.8'
+        jvmTarget = JavaVersion.VERSION_11
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
-    lintOptions {
-        disable 'InvalidPackage'
-    }
 
     defaultConfig {
         // Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "de.wger.flutter"
-        minSdkVersion 21
-        targetSdkVersion 34
-        versionCode flutterVersionCode.toInteger()
-        versionName flutterVersionName
+        minSdk = flutter.minSdkVersion
+        targetSdk = flutter.targetSdkVersion
+        versionCode = flutter.versionCode
+        versionName = flutter.versionName
     }
 
     signingConfigs {
@@ -71,8 +55,6 @@ android {
     }
     buildTypes {
         release {
-            // TODO: Add your own signing config for the release build.
-            // Signing with the debug keys for now, so `flutter run --release` works.
             signingConfig signingConfigs.release
         }
         debug {