Fix failing oauth2 test

The presence of the state parameter which has no QPROPERTY
counterpart in QgsAuthOAuth2Config was causing the
conversion for json to qobject to fail.

Author: nyalldawson

tests/src/python/test_authmanager_oauth2_ows.py

@@ -81,7 +81,6 @@ def setup_oauth(username, password, token_uri, refresh_token_uri='', authcfg_id=
         "requestTimeout": '30',
         "requestUrl": "",
         "scope": "",
-        "state": "",
         "tokenUrl": token_uri,
         "username": username,
         "version": 1