MediaGallery: avoid exception if scale is 0

Change-Id: Id75a19411463866440cd03d6c9fb656c4320c5f1

jami-android/app/src/main/java/cx/ring/adapters/ConversationMediaGalleryAdapter.kt

@@ -151,7 +151,7 @@ class ConversationMediaGalleryAdapter(
             val scaleX = videoRatio / screenRatio
             if (scaleX >= 1f) {
                 video.video.scaleX = scaleX
-            } else {
+            } else if (scaleX != 0f){
                 video.video.scaleY = 1f / scaleX
             }
         }