admin-verify: fix error message handling stable

admin-verify: fix error message handling

`dirstate.verify` used to return tuples but does not anymore, it returns
the pre-formatted error message, which is a nicer interface anyway.

--- a/mercurial/admin/verify.py	Mon May 06 12:31:29 2024 +0200
+++ b/mercurial/admin/verify.py	Mon May 06 16:16:15 2024 +0200
@@ -38,7 +38,7 @@
     is_narrow = requirements.NARROW_REQUIREMENT in repo.requirements
     narrow_matcher = repo.narrowmatch() if is_narrow else None
     for err in repo.dirstate.verify(m1, m2, parent1, narrow_matcher):
-        ui.warn(err[0] % err[1:])
+        ui.warn(err)
         errors += 1
 
     return errors