Versioning rust (firefox91 again)

[David Brownlee <abs%absd.org@localhost>]

Just a comment that with the latest rust version, firefox91 appears to
be non-buildable again - looks like it's bundled version of mp4parse
will not build with more modern rust. It may be possible to copy in a
more recent version of mp4parse, or patch the bundled version, but I
thought I'd raise the possibility of keeping an older version of rust
around for this kind of case (Presumably it would depend on whether
other packages have issues and/or if firefox91 is considered valuable
enough :)

Build error below for reference..

David


error[E0277]: the trait bound `u64: Mul<NonZeroU8>` is not satisfied
    --> /var/obj/pkg/www/firefox91/work/firefox-91.13.0/third_party/rust/mp4parse/src/lib.rs:2318:62
     |
2318 |                 static_assertions::const_assert!(<$lhs>::MAX *
<$rhs>::MAX <= <$output>::MAX);
     |                                                              ^
no implementation for `u64 * NonZeroU8`