Fix Postgres default insert sql

src/NPoco/DatabaseTypes/PostgreSQLDatabaseType.cs

@@ -22,7 +22,7 @@ public override object ExecuteInsert(Database db, IDbCommand cmd, string primary
         {
             if (primaryKeyName != null)
             {
-                cmd.CommandText += string.Format("returning {0} as NewID", EscapeSqlIdentifier(primaryKeyName));
+                cmd.CommandText += string.Format(" returning {0} as NewID", EscapeSqlIdentifier(primaryKeyName));
                 return db.ExecuteScalarHelper(cmd);
             }
             else