Error when editables don't match Requires-Python (#2194)

## Summary

Closes https://github.com/astral-sh/uv/issues/2192.

## Test Plan

(Needs tests.)

crates/uv-resolver/src/python_requirement.rs

@@ -22,12 +22,12 @@ impl PythonRequirement {
     }
 
     /// Return the installed version of Python.
-    pub(crate) fn installed(&self) -> &Version {
+    pub fn installed(&self) -> &Version {
         &self.installed
     }
 
     /// Return the target version of Python.
-    pub(crate) fn target(&self) -> &Version {
+    pub fn target(&self) -> &Version {
         &self.target
     }