Fix DefaultExpected::into_owned lifetime

[Zollerboy1]

This PR changes the lifetime returned from DefaultExpected::into_owned to be generic.

This follows the pattern of other into_owned methods in the crate, like RichPattern::into_owned or RichReason::into_owned.

The current implementation has a fixed 'static lifetime return, which doesn't work for me because I have tokens with a non-static lifetime.
My current workaround is to reimplement into_owned, which is awkward because of DefaultExpected's #[non_exhaustive]-ness:

match e {
    DefaultExpected::Token(t) => DefaultExpected::Token(t.into_owned()),
    DefaultExpected::Any => DefaultExpected::Any,
    DefaultExpected::SomethingElse => DefaultExpected::SomethingElse,
    DefaultExpected::EndOfInput => DefaultExpected::EndOfInput,
    _ => panic!("Unexpected expected kind"),
}

[zesterer]

Thanks, nice catch!