* gptel.el: Bump version and update package description.
* gptel-kagi.el (gptel--parse-response, gptel--request-data,
gptel--parse-buffer, gptel-make-kagi): Add new file and support
for the Kagi FastGPT LLM API. Streaming and setting model
parameters (temperature, max tokesn) are not supported by the API.
A Kagi backend can be added with `gptel-make-kagi`.
* README.org: Update with instructions for Kagi.
