fix: Only try again load mxc image on io exception

lib/widgets/mxc_image.dart

@@ -1,3 +1,4 @@
+import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
@@ -110,7 +111,7 @@ class _MxcImageState extends State<MxcImage> {
     }
     try {
       await _load();
-    } catch (_) {
+    } on IOException catch (_) {
       if (!mounted) return;
       await Future.delayed(widget.retryDuration);
       _tryLoad(_);