Address Android 12 component exporting rule

CHANGELOG.TXT

@@ -1,3 +1,7 @@
+v2.7.4
+Addressed Android 12 component exporting rule.
+See: https://developer.android.com/about/versions/12/behavior-changes-12#exported
+
 v2.7.3
 Added Android APK signing.
 

android/app/src/main/AndroidManifest.xml

@@ -6,6 +6,7 @@
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"
+            android:exported="true"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"

pubspec.yaml

@@ -11,7 +11,7 @@ description: O aplicație de vizualizare a datelor puse la dispoziție de Inform
 # In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
 # Read more about iOS versioning at
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
-version: 2.7.3
+version: 2.7.4
 
 environment:
   sdk: ">=2.12.0 <3.0.0"