Continue to fix deprecation warnings

lib/ui/widgets/FrienshipStatusWidget.dart

@@ -47,7 +47,7 @@ class _FriendshipStatusWidgetState extends State<FriendshipStatusWidget> {
 
     // No request sent yet
     if (widget.status.noRequestExchanged) {
-      return RaisedButton(
+      return ElevatedButton(
         child: Text(tr("Send request").toUpperCase()),
         onPressed: () =>
             executeRequest(() => _friendsHelper.sendRequest(friendID)),
@@ -56,12 +56,13 @@ class _FriendshipStatusWidgetState extends State<FriendshipStatusWidget> {
 
     // Already sent a friendship request
     if (widget.status.sentRequest) {
-      return RaisedButton(
+      return ElevatedButton(
         child: Text(
           tr("Cancel request").toUpperCase(),
           style: WhiteTextColorStyle,
         ),
-        color: Colors.red,
+        style:
+            ButtonStyle(backgroundColor: MaterialStateProperty.all(Colors.red)),
         onPressed: () =>
             executeRequest(() => _friendsHelper.cancelRequest(friendID)),
       );
@@ -94,7 +95,7 @@ class _FriendshipStatusWidgetState extends State<FriendshipStatusWidget> {
     }
 
     // The two users are friends, offers to follow him
-    return RaisedButton(
+    return ElevatedButton(
       child: Text((widget.status.following ? tr("Following") : tr("Follow"))
           .toUpperCase()),
       onPressed: () => executeRequest(() =>

lib/ui/widgets/init_widget.dart

@@ -153,8 +153,7 @@ class _InitializeWidgetState extends SafeState<InitializeWidget> {
         SizedBox(
           height: 30,
         ),
-        RaisedButton(
-          color: Colors.indigo,
+        ElevatedButton(
           onPressed: () => _tryConnect(),
           child: Text(tr("Try again")),
         ),

lib/ui/widgets/tablet_mode/user_page_tablet.dart

@@ -135,7 +135,7 @@ class _UserPageTabletState extends State<UserPageTablet> {
               // Private messages
               !_isCurrentUser
                   ? Expanded(
-                      child: OutlineButton(
+                      child: OutlinedButton(
                       onPressed: () =>
                           openPrivateConversation(context, _userInfo.id),
                       child: Icon(Icons.message),