chore: update fontFamily in button theme (#4251)

Author: hyj1204

frontend/appflowy_flutter/lib/mobile/presentation/database/board/widgets/mobile_board_trailing.dart

@@ -118,6 +118,9 @@ class _MobileBoardTrailingState extends State<MobileBoardTrailing> {
                 icon: const Icon(Icons.add),
                 label: Text(
                   LocaleKeys.board_column_newGroup.tr(),
+                  style: style.textTheme.bodyMedium!.copyWith(
+                    fontWeight: FontWeight.w600,
+                  ),
                 ),
                 onPressed: () => setState(
                   () => isEditing = true,

frontend/appflowy_flutter/lib/workspace/application/settings/appearance/mobile_appearance.dart

@@ -119,8 +119,9 @@ class MobileAppearance extends BaseAppearance {
           fixedSize: MaterialStateProperty.all(const Size.fromHeight(48)),
           elevation: MaterialStateProperty.all(0),
           textStyle: MaterialStateProperty.all(
-            const TextStyle(
+            TextStyle(
               fontSize: 14,
+              fontFamily: fontStyle.fontFamily,
               fontWeight: FontWeight.w600,
             ),
           ),
@@ -139,8 +140,9 @@ class MobileAppearance extends BaseAppearance {
       outlinedButtonTheme: OutlinedButtonThemeData(
         style: ButtonStyle(
           textStyle: MaterialStateProperty.all(
-            const TextStyle(
+            TextStyle(
               fontSize: 14,
+              fontFamily: fontStyle.fontFamily,
               fontWeight: FontWeight.w500,
             ),
           ),