chore: bump version to 5.3.1-beta.1 and update seekMix function to emit current time with seek event

packages/artplayer/package.json

@@ -1,6 +1,6 @@
 {
   "name": "artplayer",
-  "version": "5.3.0",
+  "version": "5.3.1-beta.1",
   "description": "ArtPlayer.js is a modern and full featured HTML5 video player",
   "author": "Harvey Zack <laozhaochaguan@gmail.com>",
   "license": "MIT",