Fix greeter monitor deploy

deploy/monitor-dep.yaml

@@ -16,7 +16,7 @@ spec:
       containers:
       - name: monitor
         image: {{ CI_REGISTRY_IMAGE }}/grpc:latest
-        command: ["greeter_monitor.py"]
+        command: ["python3", "-u", "greeter_monitor.py"]
         env:
         - name: GRPC_SVC
           value: grpc-svc