cockroachDB doesn't support this syntax (#1509)

store/cockroach/cockroach.go

@@ -277,7 +277,7 @@ func (s *sqlStore) initDB() error {
 	s.readOffset = readOffset
 	write, err := s.db.Prepare(fmt.Sprintf(`INSERT INTO %s.%s(key, value, expiry)
 		VALUES ($1, $2::bytea, $3)
-		ON CONFLICT ON CONSTRAINT %s_pkey
+		ON CONFLICT (key)
 		DO UPDATE
 		SET value = EXCLUDED.value, expiry = EXCLUDED.expiry;`, s.database, s.table, s.table))
 	if err != nil {