Drop support for Python 3.9 #1263

Summary

Remove Python 3.9 from the supported Python versions in Warp.

Motivation

Python 3.9 reached end-of-life in October 2025 and is no longer receiving security fixes from the CPython team.

Beyond the CPython EOL itself, optional Warp dependencies have also stopped supporting Python 3.9 and are no longer security-patching their releases on 3.9. Continuing to ship Warp wheels for 3.9 gives a false sense of support while the underlying ecosystem has moved on.

Dropping 3.9 will allow us to:

• Use language features available from Python 3.10+ (e.g., match statements, X | Y union types in type hints, parenthesized context managers).
• Reduce CI matrix size and maintenance burden.
• Align with the ecosystem of our dependencies.

Scope

• Remove cp39 from wheel build matrices (CI, packaging scripts).
• Update python_requires in pyproject.toml to >=3.10.
• Remove any 3.9-specific compatibility code or workarounds.
• Update documentation to reflect the new minimum Python version.