Re: [VOTE] Release Apache Burr (Incubating) 0.43.0 RC1

-1 (binding).

The release artifacts declare Requires-Python: >=3.9, and the release
instructions also list Python 3.9+ as supported.

In a clean Python 3.9 container, installing the RC1 wheel with the [cli] extra
succeeds, but both `burr --help` and `import burr.cli.__main__` fail with:

TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

The failure comes from `dict | None` in burr/cli/__main__.py, which requires
Python 3.10+. The release-validation workflow explicitly skips Python 3.9
because of this known incompatibility.

This should be fixed or the declared minimum Python version should be changed
before release.