Improve 'any' search message during `uv python install` (#4940)
Special cases the `Any` request in output
e.g.,
```
❯ cargo run -q -- python install --isolated
warning: `uv python install` is experimental and may change without warning.
Searching for Python installations
Found existing installation: cpython-3.12.3-macos-aarch64-none
Python is already available. Use `uv python install <request>` to install a specific version.
```
instead of
```
❯ cargo run -q -- python install --isolated
warning: `uv python install` is experimental and may change without warning.
Searching for Python versions matching: any Python
Found existing installation for any Python: cpython-3.12.3-macos-aarch64-none
Python is already available. Use `uv python install <request>` to install a specific version.
```
