change CachePolicy for replace to WRITE_ONLY

this seems to avoid that on a second load without to use replace, an old image from cache is loaded

Signed-off-by: Marcel Hibbe <dev@mhibbe.de>

app/src/main/java/com/nextcloud/talk/extensions/ImageViewExtensions.kt

@@ -103,7 +103,7 @@ private fun ImageView.loadAvatarInternal(
 ): io.reactivex.disposables
 .Disposable {
     val cachePolicy = if (replace) {
-        CachePolicy.DISABLED
+        CachePolicy.WRITE_ONLY
     } else {
         CachePolicy.ENABLED
     }