Add dummy secret key

docker-compose.yml

@@ -31,6 +31,7 @@ services:
       DJANGO_ALLOWED_HOSTS: "*" # Change this in production
       ALLOW_ADMIN_INITIATION_VIA_CLI: "true" # Change this in production
       FLAGSMITH_DOMAIN: "localhost:8000" # Change this in production
+      DJANGO_SECRET_KEY: "secret" # Change this in production
       # PREVENT_SIGNUP: "true" # Uncomment to prevent additional signups
       # ENABLE_ADMIN_ACCESS_USER_PASS: "true" # set to "true" to enable access to the /admin/ Django backend via your username and password
       # ALLOW_REGISTRATION_WITHOUT_INVITE: "true"