Convert to str the elements from the pod args list

When tobiko starts a pod to run background tests from it, all the
elements from the `args` list have to be converted to strings.
For example, when `interval` is configured to a certain integer value,
that value has to be converted to string.

Change-Id: Ib2c7ec05b06965a72a2d8ff876b4af7684e96edb

tobiko/podified/_openshift.py

@@ -391,7 +391,9 @@ def _start_pod(cmd, args, pod_name, pod_image):
                 "name": pod_name,
                 "image": pod_image,
                 "command": cmd,
-                "args": args,
+                # All items from args have to be converted to
+                # strings, otherwise the pod creation may fail
+                "args": [str(arg) for arg in args],
             }],
             "restartPolicy": "Never"
         }