Ensure virtual environment is compatible with interpreter on sync (#12884)

It was possible that a virtual environment became out of sync with the
interpreter it pointed to (for example, if a symlink was changed to an
updated Python version). In such a case, `pyvenv.cfg` and
`activate_this.py` would no longer be correct. This PR detects when the
`version` (`venv` module) or `version_info` (uv and `virtualenv`) field
in `pyvenv.cfg` is out of sync with the interpreter. In such a case, uv
recreates the virtual environment.

Closes #12461

crates/uv-python/src/environment.rs

@@ -355,4 +355,13 @@ impl PythonEnvironment {
                 .unwrap_or(false)
         }
     }
+
+    /// If this is a virtual environment (indicated by the presence of
+    /// a `pyvenv.cfg` file), this returns true if the `pyvenv.cfg` version
+    /// is the same as the interpreter Python version. Also returns true
+    /// if this is not a virtual environment.
+    pub fn matches_interpreter(&self, interpreter: &Interpreter) -> bool {
+        let Ok(cfg) = self.cfg() else { return true };
+        cfg.matches_interpreter(interpreter)
+    }
 }