test(auth): expect build_metadata issuer without trailing slash

Remove the Pydantic AnyUrl xfail now that routes.strip trailing slashes,
and assert issuer against the canonical form.

Author: piyushbag

tests/client/test_auth.py

@@ -1529,9 +1529,6 @@ async def mock_callback() -> AuthorizationCodeResult:
             "https://auth.example.com/register",
             "https://auth.example.com/revoke",
             id="simple-url",
-            marks=pytest.mark.xfail(
-                reason="Pydantic AnyUrl adds trailing slash to base URLs - fixed in Pydantic 2.12+"
-            ),
         ),
         pytest.param(
             "https://auth.example.com/",
@@ -1570,7 +1567,7 @@ def test_build_metadata(
 
     assert metadata.model_dump(exclude_defaults=True, mode="json") == snapshot(
         {
-            "issuer": Is(issuer_url),
+            "issuer": Is(issuer_url.rstrip("/")),
             "authorization_endpoint": Is(authorization_endpoint),
             "token_endpoint": Is(token_endpoint),
             "registration_endpoint": Is(registration_endpoint),