Fix discovery of pre-release managed Python versions in range requests (#13330)
We have test coverage for this elsewhere, but managed Python versions
are a distinct case because we know the _full_ version before querying
the interpreter (whereas, when we find them on the `PATH`, we usually
only know `X.y` from the file name).
This pre-filter logic now matches our subsequent logic at
https://github.com/astral-sh/uv/blob/060be9cef197d83e5546fb1be10e8e8373a1cfc6/crates/uv-python/src/discovery.rs#L2146-L2149
https://github.com/astral-sh/uv/pull/13330/commits/060be9cef197d83e5546fb1be10e8e8373a1cfc6
shows the snapshot change.