build: Use Flutter 3.19.6 for Linux

lib/pages/chat/chat_view.dart

@@ -303,7 +303,8 @@ class ChatView extends StatelessWidget {
                                 clipBehavior: Clip.hardEdge,
                                 color: Theme.of(context)
                                     .colorScheme
-                                    .surfaceContainerHighest,
+                                    // ignore: deprecated_member_use
+                                    .surfaceVariant,
                                 borderRadius: const BorderRadius.all(
                                   Radius.circular(24),
                                 ),

lib/pages/chat/events/message.dart

@@ -77,7 +77,8 @@ class Message extends StatelessWidget {
     final client = Matrix.of(context).client;
     final ownMessage = event.senderId == client.userID;
     final alignment = ownMessage ? Alignment.topRight : Alignment.topLeft;
-    var color = Theme.of(context).colorScheme.surfaceContainerHighest;
+    // ignore: deprecated_member_use
+    var color = Theme.of(context).colorScheme.surfaceVariant;
     final displayTime = event.type == EventTypes.RoomCreate ||
         nextEvent == null ||
         !event.originServerTs.sameEnvironment(nextEvent!.originServerTs);

lib/pages/chat/typing_indicators.dart

@@ -81,7 +81,8 @@ class TypingIndicators extends StatelessWidget {
                   padding: const EdgeInsets.only(top: topPadding),
                   child: Material(
                     color:
-                        Theme.of(context).colorScheme.surfaceContainerHighest,
+                        // ignore: deprecated_member_use
+                        Theme.of(context).colorScheme.surfaceVariant,
                     borderRadius: const BorderRadius.only(
                       topLeft: Radius.circular(2),
                       topRight: Radius.circular(AppConfig.borderRadius),

lib/pages/homeserver_picker/homeserver_app_bar.dart

@@ -93,7 +93,8 @@ class HomeserverAppBar extends StatelessWidget {
               : null,
           fillColor: FluffyThemes.isColumnMode(context)
               ? Theme.of(context).colorScheme.surface
-              : Theme.of(context).colorScheme.surfaceContainerHighest,
+              // ignore: deprecated_member_use
+              : Theme.of(context).colorScheme.surfaceVariant,
           prefixText: '${L10n.of(context)!.homeserver}: ',
           hintText: L10n.of(context)!.enterYourHomeserver,
           suffixIcon: const Icon(Icons.search),

lib/pages/login/login_view.dart

@@ -24,7 +24,8 @@ class LoginView extends StatelessWidget {
 
     final textFieldFillColor = FluffyThemes.isColumnMode(context)
         ? Theme.of(context).colorScheme.surface
-        : Theme.of(context).colorScheme.surfaceContainerHighest;
+        // ignore: deprecated_member_use
+        : Theme.of(context).colorScheme.surfaceVariant;
 
     return LoginScaffold(
       enforceMobileMode: Matrix.of(context).client.isLogged(),

lib/pages/user_bottom_sheet/user_bottom_sheet_view.dart

@@ -120,7 +120,8 @@ class UserBottomSheetView extends StatelessWidget {
                     padding: const EdgeInsets.all(12.0),
                     child: Material(
                       color:
-                          Theme.of(context).colorScheme.surfaceContainerHighest,
+                          // ignore: deprecated_member_use
+                          Theme.of(context).colorScheme.surfaceVariant,
                       borderRadius:
                           BorderRadius.circular(AppConfig.borderRadius),
                       child: ListTile(