Sort ManagedPythonInstallation by version

[j178]

Summary

Resolves #5139

PythonInstallationKey was sorted as a string, which caused 3.8 to appear before 3.11. This update changes the sorting of PythonInstallationKey to be a descending order by version.

Test Plan

$ cargo run -- python install 3.8 3.12
$ cargo run -- tool run -v python -V
DEBUG uv 0.2.25
warning: `uv tool run` is experimental and may change without warning.
DEBUG Searching for Python interpreter in managed installations, system path, or `py` launcher
DEBUG Searching for managed installations at `C:\Users\xx\AppData\Roaming\uv\data\python`
DEBUG Found managed Python `cpython-3.12.3-windows-x86_64-none`
DEBUG Found cpython 3.12.3 at `C:\Users\xx\AppData\Roaming\uv\data\python\cpython-3.12.3-windows-x86_64-none\install\python.exe` (managed installations)
DEBUG Using request timeout of 30s
DEBUG Using request timeout of 30s
DEBUG Acquired lock for `C:\Users\nigel\AppData\Roaming\uv\data\tools`
DEBUG Using existing environment for tool `httpx`: C:\Users\xx\AppData\Roaming\uv\data\tools\httpx
DEBUG Using existing tool `httpx`
DEBUG Running `httpx -v`

[zanieb]

Thanks!