fix bug causing a TypeError when the webserver returns a non-json response
Wenn der Webserver einen nicht-JSON Antwort liefert, erhält man folgenden Fehler:
Traceback (most recent call last):
File "...", line 113, in <module>
zones = client.execute_ta([
File ".../lib/python3.10/site-packages/netdb_client/api31/__init__.py", line 29, in execute_ta
raise ValueError(f'Request returned unexpected results ({res.status_code}: {res.reason}). Result: \n{pformat(res.json()) if "json" in res.headers["content-type"] else res.text()}')
TypeError: 'str' object is not callable