Python 3.9 support

[chowesasana]

Based on this thread, there is some willingness to provide Python 3.9 support for this library.

As much as we'd like to migrate to Python 3.10+, it's difficult to migrate enterprise codebases before official EOL status.

I'm curious what the process would be for making such a change? I'm assuming there's more work beyond just putting up a PR with 3.9 compatible code.

Happy to assist in this effort if necessary.

[Kludex]

I already fixed that on my PR in Pydantic AI. I'm just not supporting MCP on 3.9, but it didn't blocked my work.

[chowesasana]

@Kludex I'm confused - is your plan to raise the minimum Python version in your branch to 3.10? I don't think your branch will work with Python 3.9 as you'll be unable to install the MCP dependency.

[Kludex]

No, mcp is an optional dependency that can only be installed if you have python 3.10+.

[chowesasana]

Working 3.9 branch here: main...chowesasana:python-sdk:python-39-compat

Tests & type-checking pass.

[Kludex]

The Python MCP will not support Python 3.9 given that it's approaching EOF.

[NN---]

Hello, @Kludex can you reconsider please support of Python 3.9 ?
There are still system that are supported but have Python 3.9 only.
This makes it more difficult for me to use this module.