Catch broken mac_ver() (#11396)

A user reported a homebrew Python that would raise an exception in the
interpreter probing script because `platform.mac_ver()` returned `('',
('', '', ''), '')` on his installation due to
https://github.com/Homebrew/homebrew-core/issues/206778

This is easy enough to catch and show a proper error message instead of
the Python backtrace.

crates/uv-python/src/interpreter.rs

@@ -698,6 +698,8 @@ enum InterpreterInfoResult {
 pub enum InterpreterInfoError {
     #[error("Could not detect a glibc or a musl libc (while running on Linux)")]
     LibcNotFound,
+    #[error("Broken Python installation, `platform.mac_ver()` returned an empty value, please reinstall Python")]
+    BrokenMacVer,
     #[error("Unknown operating system: `{operating_system}`")]
     UnknownOperatingSystem { operating_system: String },
     #[error("Python {python_version} is not supported. Please use Python 3.8 or newer.")]