[Pkg-rust-maintainers] Updates to the trixie freeze policy

[Peter Green]

 >Milestone 1: Toolchain and d-i freeze
 >
 >
 >Milestone 2 (Milestone 1 + 2 months): Transition freeze

The big question, for those of us who were anticiapting a
schedule similar to trixie is does this mean. Toolchain
freeze two months earlier than anticipated or transition
freeze two months later than anticipated.

As we stated in bug 1084048 we would like to get support
for rust 2024 edition into trixie. On the assumption of a
toolchain freeze in late January this seemed tight but
doable. With a toolchain freeze at the end of this month
it would not be doable without an exception.