Prepare 0.4.0 release

cellxgene_gateway/backend_cache.py

@@ -8,11 +8,10 @@
 # the specific language governing permissions and limitations under the License.
 
 import time
+from http import HTTPStatus
 from threading import Thread
 from typing import List
 
-from http import HTTPStatus
-
 from cellxgene_gateway import env
 from cellxgene_gateway.cache_entry import CacheEntry, CacheEntryStatus
 from cellxgene_gateway.cache_key import CacheKey