Report Python versions in pyvenv.cfg version mismatch (#13027)

When working on #13025 I noticed this message was lacking versions,
which seems frustrating if you're debugging things.

I refactored the general `matches_interpreter` utilities that were added
in https://github.com/astral-sh/uv/pull/12884 into a more purpose-fit
function that returns an `Option` with the versions if there's a
mismatch.

crates/uv-python/src/virtualenv.rs

@@ -11,7 +11,7 @@ use thiserror::Error;
 use uv_pypi_types::Scheme;
 use uv_static::EnvVars;
 
-use crate::{Interpreter, PythonVersion};
+use crate::PythonVersion;
 
 /// The layout of a virtual environment.
 #[derive(Debug)]
@@ -270,18 +270,6 @@ impl PyVenvConfiguration {
         self.include_system_site_packages
     }
 
-    /// Returns true if the virtual environment has the same `pyvenv.cfg` version
-    /// as the interpreter Python version. Also returns true if there is no version.
-    pub fn matches_interpreter(&self, interpreter: &Interpreter) -> bool {
-        self.version.as_ref().is_none_or(|version| {
-            interpreter.python_major() == version.major()
-                && interpreter.python_minor() == version.minor()
-                && version
-                    .patch()
-                    .is_none_or(|patch| patch == interpreter.python_patch())
-        })
-    }
-
     /// Set the key-value pair in the `pyvenv.cfg` file.
     pub fn set(content: &str, key: &str, value: &str) -> String {
         let mut lines = content.lines().map(Cow::Borrowed).collect::<Vec<_>>();