Replace sized-chunks and upgrade crossbeam-channel as reported by cargo audit

[doitian]

error: Vulnerable crates found!
ID:       RUSTSEC-2020-0041
Crate:    sized-chunks
Version:  0.1.2
Date:     2020-09-06
URL:      https://rustsec.org/advisories/RUSTSEC-2020-0041
Title:    Multiple soundness issues in Chunk and InlineArray
Solution:  No safe upgrade is available!
Dependency tree: 
sized-chunks 0.1.2
ID:       RUSTSEC-2020-0041
Crate:    sized-chunks
Version:  0.6.2
Date:     2020-09-06
URL:      https://rustsec.org/advisories/RUSTSEC-2020-0041
Title:    Multiple soundness issues in Chunk and InlineArray
Solution:  No safe upgrade is available!
Dependency tree: 
sized-chunks 0.6.2
error: 1 warning found
Crate:    crossbeam-channel
Version:  0.4.3
Warning:  package has been yanked!
Dependency tree: 
crossbeam-channel 0.4.3

CKB itself locks crossbeam-channel at 0.3.9. The version 0.4.3 is a dependency of atomic-shim. The following command can upgrade only crossbeam-channel 0.4.3

cargo update -p crossbeam-channel:0.4.3

Since "No safe upgrade is available!" for sized-chunks, we have to find an alternative crate or write one ourselves.

[yangby-cryptape]

Ref: #2266