Define app bar brightness, increase minimum dart version and adapt comments to non-upgradable dependencies

lib/ui/shared/app_colors.dart

@@ -27,3 +27,6 @@ const Color whiteColor = Colors.white;
 const Color redColor = Colors.red;
 const Color orangeColor = Colors.orange;
 const Color greenColor = Colors.green;
+
+/// Theme
+const Brightness appBarBrightness = Brightness.dark;

lib/ui/widgets/my_appbar.dart

@@ -12,7 +12,7 @@ class MyAppBar extends AppBar {
             key: key,
             title: Row(children: <Widget>[title]),
             actions: _renderIconButtons(actionWidgets, enableAbout),
-            brightness: Brightness.dark,
+            brightness: appBarBrightness,
             backgroundColor: primaryAccentColor);
 
   static List<Widget> _renderIconButtons(List<Widget> actionWidgets, bool aboutEnabled) {

pubspec.yaml

@@ -14,7 +14,7 @@ description: A mobile client for FileBin.
 version: 1.3.3+12
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: ">=2.10.5 <3.0.0"
 
 dependencies:
   flutter:
@@ -25,7 +25,7 @@ dependencies:
   flutter_translate: 3.0.0
   provider: 5.0.0
   stacked: 2.1.1
-  get_it: 6.1.1 # major changes > 7
+  get_it: 6.1.1 # stacked requires ^6
   logger: 1.0.0
   shared_preferences: 2.0.5
   http: 0.13.3
@@ -40,14 +40,14 @@ dependencies:
   permission_handler: 7.1.0
   package_info: 2.0.0
   simple_gesture_detector: 0.2.0
-  json_annotation: 3.1.1
+  json_annotation: 3.1.1 # requires null-safety update
 
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  build_runner: 1.11.5
-  built_value_generator: 8.0.4
-  json_serializable: 3.5.1
+  build_runner: 1.11.5 # requires null-safety update
+  built_value_generator: 8.0.4 # requires null-safety update
+  json_serializable: 3.5.1 # requires null-safety update
 
 # For information on the generic Dart part of this file, see the
 # following page: https://www.dartlang.org/tools/pub/pubspec