Fix query-values priority

When used with an upsert clause, query-values was not being rendered
with the correct priority. The provided test fails on master and passes
on this branch. It was previously rendering the SQL as:

```
INSERT INTO distributors (did, dname)
ON CONFLICT ON CONSTRAINT distributors_pkey DO NOTHING
(SELECT ?, ?)
```

which is not valid SQL. The below snippet from psql demonstrates this
not working:

```
muncher=# insert into foo (id) select 1 on conflict do nothing;
INSERT 0 1
muncher=# insert into foo (id) on conflict do nothing (select 1);
ERROR:  syntax error at or near "on"
LINE 1: insert into foo (id) on conflict do nothing (select 1);
```

Author: b-ryan

src/honeysql_postgres/format.cljc

@@ -45,7 +45,7 @@
           :offset 210
           :lock 215
           :values 220
-          :query-values 250}
+          :query-values 221}
          custom-additions))
 
 (defn override-default-clause-priority

test/honeysql_postgres/postgres_test.cljc

@@ -7,8 +7,8 @@
                                                          add-column partition-by insert-into-as
                                                          create-table rename-table drop-table
                                                          window create-view over with-columns]]
-            [honeysql.helpers :as sqlh :refer [insert-into values where select
-                                               from order-by update sset]]
+            [honeysql.helpers :as sqlh :refer [insert-into values where select columns
+                                               from order-by update sset query-values]]
             [honeysql.core :as sql]
             [clojure.test :as test :refer [deftest is testing]]))
 
@@ -45,6 +45,13 @@
                (values [{:did 23 :dname "Foo Distributors"}])
                (on-conflict :did)
                (do-update-set! [:dname "EXCLUDED.dname || ' (formerly ' || d.dname || ')'"])
+               sql/format)))
+    (is (= ["INSERT INTO distributors (did, dname) (SELECT ?, ?) ON CONFLICT ON CONSTRAINT distributors_pkey DO NOTHING" 1 "whatever"]
+           (-> (insert-into :distributors)
+               (columns :did :dname)
+               (query-values (select 1 "whatever"))
+               (upsert (-> (on-conflict-constraint :distributors_pkey)
+                           do-nothing))
                sql/format)))))