fixed version and selector

k8s/CONF/DBs/mongo-express-deployment.yaml

-apiVersion: extensions/v1beta1
+apiVersion: apps/v1
 kind: Deployment
 metadata:
   namespace: conf
@@ -10,6 +10,9 @@ metadata:
     io.kompose.service: mongo-express
   name: mongo-express
 spec:
+  selector:
+    matchLabels:
+      io.kompose.service: mongo-express
   replicas: 1
   strategy: {}
   template: