Fix PQFormat instances

Author: theophile-scrive

src/Database/PostgreSQL/PQTypes/Format.hs

@@ -86,13 +86,13 @@ instance PQFormat Double where
   pqFormat = BS.pack "%float8"
 
 instance PQFormat Word16 where
-  pqFormat = BS.pack "%word2"
+  pqFormat = BS.pack "%int2"
 
 instance PQFormat Word32 where
-  pqFormat = BS.pack "%word4"
+  pqFormat = BS.pack "%int4"
 
 instance PQFormat Word64 where
-  pqFormat = BS.pack "%word8"
+  pqFormat = BS.pack "%int8"
 
 -- CHAR