fix: include cfg directive for new test case

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rxing"
-version = "0.5.3"
+version = "0.5.4"
 description="A rust port of the zxing barcode library."
 license="Apache-2.0"
 repository="https://github.com/rxing-core/rxing"

tests/cpp_qr_code_blackbox_tests.rs

@@ -328,6 +328,7 @@ fn cpp_qrcode_black_box7_test_case() {
     tester.test_black_box();
 }
 
+#[cfg(feature = "image-formats")]
 #[test]
 fn cpp_rmqr_blackbox_test_case() {
     let mut tester = common::AbstractBlackBoxTestCase::new(