Plugin cleanup and tweaks

plugins/youtube_download/yt_dlp/extractor/packtpub.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import json
 
 from .common import InfoExtractor
@@ -47,10 +45,7 @@ class PacktPubIE(PacktPubBaseIE):
     _NETRC_MACHINE = 'packtpub'
     _TOKEN = None
 
-    def _real_initialize(self):
-        username, password = self._get_login_info()
-        if username is None:
-            return
+    def _perform_login(self, username, password):
         try:
             self._TOKEN = self._download_json(
                 'https://services.packtpub.com/auth-v1/users/tokens', None,