message: Show tables test: change "NULL" to NULL
diff: @@ -27,7 +27,7 @@ TEST_CASE("Test SHOW/DESCRIBE tables", "[pragma]") {
  REQUIRE(CHECK_COLUMN(result, 1, {"INTEGER", "INTEGER"}));
  REQUIRE(CHECK_COLUMN(result, 2, {"YES", "YES"}));
  REQUIRE(CHECK_COLUMN(result, 3, {Value(), Value()}));
  - REQUIRE(CHECK_COLUMN(result, 4, {"NULL", "NULL"}));
  + REQUIRE(CHECK_COLUMN(result, 4, {Value(), Value()}));
  REQUIRE(CHECK_COLUMN(result, 5, {Value(), Value()}));
  // equivalent to PRAGMA SHOW('integers')
  result = con.Query("PRAGMA SHOW('integers')");
  @@ -36,7 +36,7 @@ TEST_CASE("Test SHOW/DESCRIBE tables", "[pragma]") {
  REQUIRE(CHECK_COLUMN(result, 1, {"INTEGER", "INTEGER"}));
  REQUIRE(CHECK_COLUMN(result, 2, {"YES", "YES"}));
  REQUIRE(CHECK_COLUMN(result, 3, {Value(), Value()}));
  - REQUIRE(CHECK_COLUMN(result, 4, {"NULL", "NULL"}));
  + REQUIRE(CHECK_COLUMN(result, 4, {Value(), Value()}));
  REQUIRE(CHECK_COLUMN(result, 5, {Value(), Value()}));
  // we can also describe views
  