container_puppet_config: python3 fix

Python3 returns an error if we write the file in text. We need to write
in binary.

Closes-Bug: #1863352
Change-Id: Ief80c917803c2143e459a74079159d958d18f153

tripleo_ansible/ansible_plugins/modules/container_puppet_config.py

@@ -412,7 +412,7 @@ class ContainerPuppetManager:
         :param path: string
         :param config: string
         """
-        f = open(path, 'w')
+        f = open(path, 'wb')
         f.write(json.dumps(config, indent=2).encode('utf-8'))
         os.chmod(path, 0o600)