Fix assert! macro usage

There is a bug in rustc that allows adding invalid trailing tokens to
the `assert!` macro call. They are currently ignored but are going to
produce errors in the future.

Fix assert! macro usage to add missing comma.

For more information, see
rust-lang/rust#60024 and
rust-lang/rust#60039

src/lib.rs

@@ -164,9 +164,9 @@ fn test_hexadecimal_decimal() {
     assert_eq!(hexadecimal_decimal(b"0007".to_vec()).unwrap(), 7);
     assert_eq!(hexadecimal_decimal(b"00000001".to_vec()).unwrap(), 1);
     assert_eq!(hexadecimal_decimal(b"0100".to_vec()).unwrap(), 256);
-    assert!(hexadecimal_decimal(b"0".to_vec()).is_err() "Must have even number of hex chars");
-    assert!(hexadecimal_decimal(b"000".to_vec()).is_err() "Must have even number of hex chars");
-    assert!(hexadecimal_decimal(b"00000".to_vec()).is_err() "Must have even number of hex chars");
+    assert!(hexadecimal_decimal(b"0".to_vec()).is_err(), "Must have even number of hex chars");
+    assert!(hexadecimal_decimal(b"000".to_vec()).is_err(), "Must have even number of hex chars");
+    assert!(hexadecimal_decimal(b"00000".to_vec()).is_err(), "Must have even number of hex chars");
     assert!(
         hexadecimal_decimal(b"1122334455667788A".to_vec()).is_err(),
         "Max 16 hex chars can be parsed"