bpo-36853: Fix suspicious.py to actually print the unused rules (GH-13579) (GH-15649)

* Fix suspicious.py to actually print the unused rules

* Fix the other `self.warn` calls
(cherry picked from commit e1786b54162e2bfb01ca5aafa19d596c4af5a803)

Co-authored-by: Anthony Sottile <asottile@umich.edu>
1 file changed