[Rust] [HEADS-UP] Planning to upgrade rust-loopdev to 0.4.0

[the Mulhern]

Hi all,

I'm planning to upgrade rust-loopdev to 0.4.0 to evade some cruft that
is in the previously released 0.2.0.

As far as I can tell, only Stratis projects stratisd,
rust-devicemapper, and rust-libcryptsetup depend on this crate.

- mulhern

-- 
The Moving Finger writes; and, having writ,
Moves on: nor all thy Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all thy Tears wash out a Word of it.
- "The Rubaiyat of Omar Khayyam", Robert Fitzgerald, translator