[fix] Vtt ext name

app/src/main/java/com/acitelight/aether/model/Video.kt

@@ -30,7 +30,7 @@ class Video(
 
     fun getSubtitle(): String {
         return if (isLocal)
-            "$localBase/videos/$klass/$id/subtitle.ass"
+            "$localBase/videos/$klass/$id/subtitle.vtt"
         else
             "${ApiClient.getBase()}api/video/$klass/$id/subtitle?token=$token"
     }

app/src/main/java/com/acitelight/aether/service/FetchManager.kt

@@ -160,7 +160,7 @@ class FetchManager @Inject constructor(
         downloadFile(
             client!!,
             video.getSubtitle(),
-            File(context.getExternalFilesDir(null), "videos/${video.klass}/${video.id}/subtitle.ass"))
+            File(context.getExternalFilesDir(null), "videos/${video.klass}/${video.id}/subtitle.vtt"))
 
         enqueue(request)
         File(context.getExternalFilesDir(null), "videos/${video.klass}/${video.id}/summary.json").writeText(Json.encodeToString(video))

app/src/main/java/com/acitelight/aether/viewModel/VideoPlayerViewModel.kt

@@ -118,9 +118,8 @@ class VideoPlayerViewModel @Inject constructor(
 
                 val mediaItem: MediaItem = if (subtitleUri != null) {
                     // prepare subtitle configuration with guessed mime type
-                    val mime = "text/vtt"
                     val subConfig = MediaItem.SubtitleConfiguration.Builder(subtitleUri)
-                        .setMimeType(mime)
+                        .setMimeType("text/vtt")
                         .build()
 
                     MediaItem.Builder()