Merge branch '22-upgrade-flutter-framework-and-dependencies' into 'master'

Resolve "Upgrade Flutter framework and dependencies"

Closes #22

See merge request !19

android/gradle.properties

 org.gradle.jvmargs=-Xmx1536M
 android.useAndroidX=true
 android.enableJetifier=true
-app.versionName=1.0.11
-app.versionCode=12
+app.versionName=1.0.12
+app.versionCode=13

lib/main.dart

@@ -18,7 +18,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   final String title;
 

pubspec.yaml

@@ -4,7 +4,7 @@ publish_to: 'none'
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: ">=2.16.1 <3.0.0"
 
 dependencies:
   flutter: