make_ct_known_logs_list.py: Make Python 3 compatible

In Python 3 keys() returns an iterable instead of a list. It's necessary to explicitly convert when you want to use as a list.
Still works with Python 2.

Fixed errors:
Traceback (most recent call last):
  File "../../components/certificate_transparency/tools/make_ct_known_logs_list.py", line 204, in <module>
    sys.exit(main())
  File "../../components/certificate_transparency/tools/make_ct_known_logs_list.py", line 199, in main
    generate_cpp_file(infile, outfile)
  File "../../components/certificate_transparency/tools/make_ct_known_logs_list.py", line 174, in generate_cpp_file
    if _is_log_once_or_currently_qualified(log):
  File "../../components/certificate_transparency/tools/make_ct_known_logs_list.py", line 161, in _is_log_once_or_currently_qualified
    return log.get("state").keys()[0] not in ("pending", "rejected")
TypeError: 'dict_keys' object is not subscriptable

Traceback (most recent call last):
  File "C:\Google\chromium\src\components\certificate_transparency\tools\make_ct_known_logs_list_unittest.py", line 238, in testSortingAndFilteringDisqualifiedLogs
    disqualified_logs = make_ct_known_logs_list._sorted_disqualified_logs(logs)
  File "C:\Google\chromium\src\components\certificate_transparency\tools\make_ct_known_logs_list.py", line 147, in _sorted_disqualified_logs
    return sorted(
  File "C:\Google\chromium\src\components\certificate_transparency\tools\make_ct_known_logs_list.py", line 87, in _is_log_disqualified
    log_state = log.get("state").keys()[0]
TypeError: 'dict_keys' object is not subscriptable

Bug: 941669
Change-Id: Iff905a290c3dc2581e1a0ff7ad8a8282ce9c050e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857121
Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Commit-Queue: Raul Tambre <raul@tambre.ee>
Auto-Submit: Raul Tambre <raul@tambre.ee>
Cr-Commit-Position: refs/heads/master@{#705592}

components/certificate_transparency/tools/make_ct_known_logs_list.py

@@ -84,7 +84,7 @@ def _get_log_ids_for_operator(logs_by_operator, operator_name):
 def _is_log_disqualified(log):
   # Disqualified logs are denoted with state="retired"
   assert (len(log.get("state").keys()) == 1)
-  log_state = log.get("state").keys()[0]
+  log_state = list(log.get("state"))[0]
   return log_state == "retired"
 
 
@@ -158,7 +158,7 @@ def _write_qualifying_logs_loginfo(f, qualifying_logs):
 
 def _is_log_once_or_currently_qualified(log):
   assert (len(log.get("state").keys()) == 1)
-  return log.get("state").keys()[0] not in ("pending", "rejected")
+  return list(log.get("state"))[0] not in ("pending", "rejected")
 
 
 def generate_cpp_file(input_file, f):