Fix lock_requires_python fixture (#6594)

crates/uv/tests/lock.rs

@@ -2735,6 +2735,8 @@ fn lock_requires_python() -> Result<()> {
            cannot be used, we can conclude that pygls>=1.1.0 cannot be used.
           And because your project depends on pygls>=1.1.0, we can conclude that your project's requirements are unsatisfiable.
 
+          hint: Pre-releases are available for pygls in the requested range (e.g., 2.0.0a1), but pre-releases weren't enabled (try: `--prerelease=allow`)
+
           hint: The `requires-python` value (>=3.7) includes Python versions that are not supported by your dependencies (e.g., pygls>=1.1.0,<=1.2.1 only supports >=3.7.9, <4). Consider using a more restrictive `requires-python` value (like >=3.7.9, <4).
     "###);