aiohttp's ClientResponse.json() validates the Content-Type header against
'application/json' by default and raises ContentTypeError for any other
value — including 'application/x-ndjson', which Ollama returns for its
OpenAI-compatible /v1/images/generations endpoint.
Pass content_type=None to skip this check while keeping all other parsing
behaviour unchanged. The fix covers image generation (openai, gemini,
automatic1111 engines) and image editing (openai, gemini engines).