fix test_type! when a NULL comes through

Author: mehcode

sqlx-test/src/lib.rs

@@ -67,7 +67,7 @@ macro_rules! test_prepared_type {
  $(
  let query = format!($crate::[< $db _query_for_test_prepared_type >]!(), $text);
 
- let rec: (bool, String, $ty, $ty) = sqlx::query_as(&query)
+ let rec: (bool, Option<String>, $ty, $ty) = sqlx::query_as(&query)
  .bind($value)
  .bind($value)
  .bind($value)