Use BatTester::default instead of BatTester::new

tests/snapshot_tests.rs

@@ -7,7 +7,7 @@ macro_rules! snapshot_tests {
         $(
             #[test]
             fn $test_name() {
-                let bat_tester = BatTester::new();
+                let bat_tester = BatTester::default();
                 bat_tester.test_snapshot(stringify!($test_name), $style);
             }
         )*