osbs-master role: fix args:creates syntax for shell cmd

roles/osbs-master/tasks/main.yml

@@ -56,6 +56,7 @@
 
 - name: generate cert for authenticating proxy - concatenate cert and key
   shell: cat {{ osbs_proxy_cert_file }} {{ osbs_proxy_key_file }} > {{ osbs_proxy_certkey_file }}
+  args:
     creates: "{{ osbs_proxy_certkey_file }}"
 
 # We need to have openshift restarted in order to configure authentication.