Test fail with new mistralai version

[medaminezghal]

Initial Checks

• I confirm that I'm using the latest version of Pydantic AI
• I confirm that I searched for my issue in https://github.com/pydantic/pydantic-ai/issues before opening this issue

Description

From mistralai>=1.8.1, this line in mistralai test will cause a problem because created should be an int according to new version in this file.

If I change from created=1704067200 if with_created else None to created=1704067200 if with_created else 0, the tests work. I don't know if the value 0 will cause any future problem. If there is no problem, I can create a PR.

Example Code

Python, Pydantic AI & LLM client version

The latest of every package.

[medaminezghal]

@Kludex @Viicos What are your thoughts about the solution?