Fix fakes3 configuration in ci yml

services/filestore/docker-compose.ci.yml

@@ -57,4 +57,6 @@ services:
 
   fakes3:
     image: adobe/s3mock
-    command: --initialBuckets=fake_user_files,fake_template_files,fake_public_files
+    environment:
+      - initialBuckets=fake_user_files,fake_template_files,fake_public_files
+