cmac nobbled by yanked/replaced upstream crate API

[queenp]

Getting the following error building something that depends on cmac.

error[E0432]: unresolved import `digest::common::BlockSizes`
  --> /path/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/cmac-0.8.0-rc.4/src/block_api.rs:11:14
   |
11 |     common::{BlockSizes, InnerInit, InnerUser},
   |              ^^^^^^^^^^
   |              |
   |              no `BlockSizes` in the root
   |              help: a similar name exists in the module: `BlockSizeUser`

I believe this is because cmac depends on an api available at (but not after) the yanked 0.2.0 crypto-common release.

https://docs.rs/crypto-common/0.2.0/crypto_common/trait.BlockSizes.html

This is missing in the new API in 0.2.1

https://docs.rs/crypto-common/latest/crypto_common/?search=blocksize

[newpavlov]

See RustCrypto/traits#2316

We plan to cut proper releases soon. For now you could use the dependency patching workaround.

[newpavlov]

The code was updated in #249.