Switch gemini request to camelCase as required by API

[piercefreeman]

From the gemini docs https://ai.google.dev/api/generate-content#text_gen_text_only_prompt-SHELL, request parameters are expected to camelCase instead of the current snake_case that's being uploaded directly:

safetySettings[]
systemInstruction
generationConfig
cachedContent

[Kludex]

You do have a point... But it's working, right? 👀

I'm on the transition to refactor the GeminiModel to use the google.genai.Client: #1373, so this will be solved there.

[piercefreeman]

@Kludex From what I'm seeing, it's not working. In the current release safety settings are not respected and always fail with MEDIUM or higher (the default value when unprovided). When I run against this branch it successfully reduces errors to NONE.

Your call on whether to merge in now or wait until your refactor!

[dmontagu]

@piercefreeman thanks for this! We'll merge and release it now, just noting that as Marcelo has indicated, the plan is to switch to using an official Google SDK in the near future. (When we do that, you'll presumably want to confirm everything still behaves properly, but also, it's probably more likely to given it will be the actual Google SDK ...)