fix: Use the right scope when getting the bigquery table usage (#181)

databuilder/extractor/base_bigquery_extractor.py

@@ -44,15 +44,15 @@ class BaseBigQueryExtractor(Extractor):
         if self.key_path:
             credentials = (
                 google.oauth2.service_account.Credentials.from_service_account_file(
-                    self.key_path, scopes=BaseBigQueryExtractor._DEFAULT_SCOPES))
+                    self.key_path, scopes=self._DEFAULT_SCOPES))
         else:
             if self.cred_key:
                 service_account_info = json.loads(self.cred_key)
                 credentials = (
                     google.oauth2.service_account.Credentials.from_service_account_info(
-                        service_account_info, scopes=BaseBigQueryExtractor._DEFAULT_SCOPES))
+                        service_account_info, scopes=self._DEFAULT_SCOPES))
             else:
-                credentials, _ = google.auth.default(scopes=BaseBigQueryExtractor._DEFAULT_SCOPES)
+                credentials, _ = google.auth.default(scopes=self._DEFAULT_SCOPES)
 
         http = httplib2.Http()
         authed_http = google_auth_httplib2.AuthorizedHttp(credentials, http=http)