changing the error message for clarity

Author: nitneuqr

src/rust/src/pkcs7.rs

@@ -775,7 +775,7 @@ fn verify_der<'p>(
                                 None => {
                                     return Err(CryptographyError::from(
                                         pyo3::exceptions::PyValueError::new_err(
-                                            "The PKCS7 data does not contain any certificate.",
+                                            "The PKCS7 data has an empty certificates attributes.",
                                         ),
                                     ));
                                 }