Migrate gemini to version 2.0 since 1.5 is being deprecated; if it costs money, just disable the endpoint for now

Here is a discussion on the issue https://discuss.ai.google.dev/t/gemini-1-5-flash-002-discontinuation-date-is-september-24-2025-its-too-short-we-hopt-at-least-5-years/47703

If it costs money to use the upgraded version, let's disable the feature's endpoint for gemini responses until a new free tier comes out or we have some form of donation/revenue system.