Fix TypeError being raised by json.dumps in policy_authority

This PS also catches TypeError raised by json.dumps if the policy
data is malformed.

For example, right now in Cinder, a policy action defined in code
is mistakenly a tuple [0] (which is a bug [1]) causing json.dumps
to throw a TypeError because a key in the dict is a tuple rather
than a string.

[0] https://github.com/openstack/cinder/blob/c6a82637fb777cec8df93ce02b2d65e8bb54c247/cinder/policies/capabilities.py#L21
[1] I1d924da3504861f027273d3319e5cf6c485d1d37

Change-Id: Idf05dc97a932cdbff2a336a91026d8104b0ec243
Depends-On: I1d924da3504861f027273d3319e5cf6c485d1d37
diff --git a/patrole_tempest_plugin/policy_authority.py b/patrole_tempest_plugin/policy_authority.py
index d2d07c0..0a1aa13 100644
--- a/patrole_tempest_plugin/policy_authority.py
+++ b/patrole_tempest_plugin/policy_authority.py
@@ -225,7 +225,7 @@
 
         try:
             policy_data = json.dumps(policy_data)
-        except ValueError:
+        except (TypeError, ValueError):
             error_message = 'Policy file for {0} service is invalid.'.format(
                 service)
             raise rbac_exceptions.RbacParsingException(error_message)