update UI at picker dialogs from the main thread

app/src/main/kotlin/com/simplemobiletools/gallery/dialogs/PickDirectoryDialog.kt

@@ -42,7 +42,9 @@ class PickDirectoryDialog(val activity: BaseSimpleActivity, val sourcePath: Stri
 
         activity.getCachedDirectories {
             if (it.isNotEmpty()) {
-                gotDirectories(activity.addTempFolderIfNeeded(it))
+                activity.runOnUiThread {
+                    gotDirectories(activity.addTempFolderIfNeeded(it))
+                }
             }
         }
 

app/src/main/kotlin/com/simplemobiletools/gallery/dialogs/PickMediumDialog.kt

@@ -39,7 +39,9 @@ class PickMediumDialog(val activity: BaseSimpleActivity, val path: String, val c
         activity.getCachedMedia(path) {
             val media = it.filter { !it.isVideo() } as ArrayList
             if (media.isNotEmpty()) {
-                gotMedia(media)
+                activity.runOnUiThread {
+                    gotMedia(media)
+                }
             }
         }