Make alloc public and bump version

[KiChjang]

Local testing of substrate is failing with:

error[E0603]: crate `alloc` is private
   --> /home/keith/.cargo/registry/src/github.com-1ecc6299db9ec823/bounded-collections-0.1.0/src/lib.rs:238:12
    |
238 |             $crate::alloc::vec![$($values),*].try_into().unwrap()
    |                     ^^^^^ private crate
    |
note: the crate `alloc` is defined here
   --> /home/keith/.cargo/registry/src/github.com-1ecc6299db9ec823/bounded-collections-0.1.0/src/lib.rs:12:1
    |
12  | extern crate alloc;
    | ^^^^^^^^^^^^^^^^^^^

when attempting to switch over to the bounded-collections crate, and hence we need to make extern crate alloc public.