Drop support for Python 3.9

[jakubno]

Note

Medium Risk
Medium risk because it changes supported runtime versions and CI toolchain pinning, which can break downstream users on 3.9 and alter release/test behavior across workflows.

Overview
Drops Python 3.9 support by bumping the Python SDK and template minimum version to Python 3.10, updating lockfiles accordingly (including removing 3.9-only deps like setuptools and tightening markers such as exceptiongroup).

Standardizes CI tooling versions across workflows by introducing a repo-level .tool-versions and wiring GitHub Actions to parse it for nodejs, pnpm, python, and poetry versions (plus minor workflow updates like setup-python@v5).

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[mishushakov]

looks fine, could you maybe make one GitHub workflow that will setup the env and use it in all workflows? there seems to be lots of duplication

[jakubno]

looks fine, could you maybe make one GitHub workflow that will setup the env and use it in all workflows? there seems to be lots of duplication

not relevant to the PR, feel free to address the issue, I think using tool-versions already simplifies it a little