Update Gemini model from 2.5-pro to 3-pro-preview (#113)

* Update Gemini model from 2.5-pro to 3-pro-preview

Co-authored-by: openhands <openhands@all-hands.dev>

Author: neubig

openhands/usage/llms/llms.mdx

@@ -26,7 +26,7 @@ Based on these findings and community feedback, these are the latest models that
 - [anthropic/claude-sonnet-4-20250514](https://www.anthropic.com/api) (recommended)
 - [anthropic/claude-sonnet-4-5-20250929](https://www.anthropic.com/api) (recommended)
 - [openai/gpt-5-2025-08-07](https://openai.com/api/) (recommended)
-- [gemini/gemini-2.5-pro](https://blog.google/technology/google-deepmind/gemini-model-thinking-updates-march-2025/)
+- [gemini/gemini-3-pro-preview](https://blog.google/products/gemini/gemini-3/)
 - [deepseek/deepseek-chat](https://api-docs.deepseek.com/)
 - [moonshot/kimi-k2-0711-preview](https://platform.moonshot.ai/docs/pricing/chat#generation-model-kimi-k2)
 
@@ -48,10 +48,6 @@ limits and monitor usage.
 
 ### Known Issues
 
-<Warning>
-As of July 2025, there are known issues with Gemini 2.5 Pro conversations taking longer than normal with OpenHands. We are continuing to investigate.
-</Warning>
-
 <Note>
 Most current local and open source models are not as powerful. When using such models, you may see long
 wait times between messages, poor responses, or errors about malformed JSON. OpenHands can only be as powerful as the

openhands/usage/llms/openhands-llms.mdx

@@ -46,7 +46,7 @@ Pricing follows official API provider rates. Below are the current pricing detai
 | devstral-small-2507 | $0.10 | N/A | $0.30 | 128,000 | 128,000 |
 | o3 | $2.00 | $0.50 | $8.00 | 200,000 | 100,000 |
 | o4-mini | $1.10 | $0.275 | $4.40 | 200,000 | 100,000 |
-| gemini-2.5-pro | $1.25 | $0.125 | $10.00 | 1,048,576 | 65,535 |
+| gemini-3-pro-preview | $2.00 | $0.125 | $12.00 | 1,048,576 | 65,535 |
 | kimi-k2-0711-preview | $0.60 | $0.15 | $2.50 | 131,072 | 131,072 |
 | qwen3-coder-480b | $0.40 | N/A | $1.60 | N/A | N/A |