fix(Session): Don't try to extract api version from service worker

It doesn't make sense to do this anyway because if it ever changed, we'd probably have to refactor the entire library.

Closes #602, #603, #604

src/core/Session.ts

@@ -296,7 +296,7 @@ export default class Session extends EventEmitter {
 
     const ytcfg = data[0][2];
 
-    const api_version = `v${ytcfg[0][0][6]}`;
+    const api_version = Constants.CLIENTS.WEB.API_VERSION;
 
     const [ [ device_info ], api_key ] = ytcfg;