fix: reset transmuxer in resetEverything to fix seeking backwards in …

…some cases (#1213)

This ultimately happens because resetEverything does not reset the gop cache. So If we seeked backwards and have a gop cache then we would throw out an entire segment as it didn't line up with our know gops.

src/segment-loader.js

@@ -1146,6 +1146,11 @@ export default class SegmentLoader extends videojs.EventTarget {
       this.transmuxer_.postMessage({
         action: 'clearAllMp4Captions'
       });
+
+      // reset the cache in the transmuxer
+      this.transmuxer_.postMessage({
+        action: 'reset'
+      });
     }
   }