refactor: Remove all the remaining six.moves import.

scripts/lib/email-mirror-postfix

@@ -48,8 +48,8 @@ import posix
 import json
 
 from urllib.parse import urljoin, urlencode
-from six.moves.urllib.request import Request, urlopen
-from six.moves.urllib.error import HTTPError
+from urllib.request import Request, urlopen
+from urllib.error import HTTPError
 from configparser import RawConfigParser
 from six import text_type
 
@@ -131,7 +131,7 @@ def send_email_mirror(rcpt_to, shared_secret, host, url, test, verify_ssl):
             "secret": shared_secret}
     req = Request(url=urljoin(host, url), data=urlencode(data).encode('utf8'))
     try:
-        urlopen(req, **request_context)  # type: ignore # six.moves.urllib.request
+        urlopen(req, **request_context)  # type: ignore # urllib.request
     except HTTPError as err:
         process_response_error(err)
 

zerver/lib/bugdown/__init__.py

@@ -55,7 +55,6 @@ import zerver.lib.alert_words as alert_words
 import zerver.lib.mention as mention
 from zerver.lib.str_utils import force_str, force_text
 from zerver.lib.tex import render_tex
-from six.moves import html_parser
 
 FullNameInfo = TypedDict('FullNameInfo', {
     'id': int,