Replace all remaining six usage with native Python 3 equivalents (#7704)

synapse/rest/client/v2_alpha/account.py

@@ -15,8 +15,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-
-from six.moves import http_client
+from http import HTTPStatus
 
 from synapse.api.constants import LoginType
 from synapse.api.errors import Codes, SynapseError, ThreepidValidationError
@@ -321,7 +320,7 @@ class DeactivateAccountRestServlet(RestServlet):
         erase = body.get("erase", False)
         if not isinstance(erase, bool):
             raise SynapseError(
-                http_client.BAD_REQUEST,
+                HTTPStatus.BAD_REQUEST,
                 "Param 'erase' must be a boolean, if given",
                 Codes.BAD_JSON,
             )