fix(go/plugins/ollama): add gpt-oss to tool supported models

[johnmccabe]

Description:

• running the go/samples/ollama-tools example with the model gpt-oss results in the following error:

  johnmccabe@dev:~/workspaces/genkit/go/samples/ollama-tools$ go run .
  Generating response with weather tool...
  Error: model "ollama/gpt-oss" does not support tool use, but tools were provided. Request: &{Config:<nil> Docs:[] Messages:[0xc000378e40 0xc000378e70] Output:0xc000378ea0 ToolChoice:auto Tools:[0xc000214600]}
  

• Updating the toolSupportedModels and rerunning with gpt-oss results in the go/samples/ollama-tools example behaving as expected:

  johnmccabe@dev:~/workspaces/genkit/go/samples/ollama-tools$ go run .
  Generating response with weather tool...
  
  ----- Final Response -----
  Here’s the current weather in Tokyo:
  
  - **Condition:** Cloudy  
  - **Temperature:** 24 °C (≈ 75 °F)  
  
  Let me know if you’d like to check another city or need more details!
  --------------------------
  

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)