Add advisory for use after free in pared <=0.3.0

[radekvit]

Use after free in Parc and Prc due to missing lifetime constraints

Affected versions of this crate didn't provide sufficient lifetime constraints to conversion
functions from alloc::sync::Arc and alloc::rc::Rc, which made it possible to create
projections of these reference counted pointers. Unlike the original reference counted pointers,
these projections could outlive original data's lifetimes.

This projected pointer could cause the original Arc's or Rc's Drop::drop to get called at
a point where the original data was no longer valid, leading to a potential use after free.

The affected functions were

• pared::prc::Prc::from_rc
• pared::prc::Prc::project
• pared::prc::Prc::try_from_rc
• pared::sync::Parc::from_arc
• pared::sync::Parc::project
• pared::sync::Parc::try_from_arc

This flaw was fixed in 108f540ea8acb6073751a1aa386085c1cdc4fd1e
by requiring that the type stored in the Arcs and Rcs passed to these functions contain T: 'static.

[djc]

LGTM, thanks!