[Go] thoughtSignature in tool calling using gemini 3 family

[mquinteiro]

There are a problem calling tools in the go framework, the bug is in other languages too, the #3921 describes the same problem but in JS.

[hugoaguirre]

Hi @mquinteiro, thanks for bringing this up. We faced this issue when adding the multi-part tool support in #3975

We will take a look at this and handle the signature in all parts as mentioned in here