Remove iot_class from manifest

Documentation has this, but hassfest checks fail if it is included.

custom_components/tuya_local/manifest.json

@@ -7,6 +7,5 @@
     "dependencies": [],
     "codeowners": ["@make-all"],
     "requirements": ["pycryptodome~=3.9","tinytuya~=1.2"],
-    "config_flow": true,
-    "iot_class": "local_polling"
+    "config_flow": true
 }