`IriStr::normalize` unexpectedly decodes percent-encoded invalid UTF-8 sequence

[yescallop]

Example:

assert!(str::from_utf8(b"\xF9\xA8\x8E\x80").is_err());
assert_eq!(IriStr::new("a:%F9%A8%8E%80").unwrap().normalize().to_string(), "a:\u{68380}");

This was found by fuzz testing. The fuzz target used was normalize_iri_against_iri_string.rs.

[lo48576]

Thank you!
This should be fixed by ff72e0a.
I'll publish the new version to crates.io later.

[lo48576]

Released as iri-string v0.7.9.