refactor: update export syntax to default for ASR and VAST plugins

packages/artplayer-plugin-asr/types/artplayer-plugin-asr.d.ts

@@ -1,8 +1,5 @@
 import type Artplayer from 'artplayer'
 
-export = artplayerPluginAsr
-export as namespace artplayerPluginAsr;
-
 interface AudioChunk {
   pcm: ArrayBuffer
   wav: ArrayBuffer
@@ -24,3 +21,5 @@ interface AsrPluginInstance {
 }
 
 declare function artplayerPluginAsr(option?: AsrPluginOption): (art: Artplayer) => AsrPluginInstance
+
+export default artplayerPluginAsr