RustCrypto crate upgrades; MSRV 1.57 (#378)

Updates all of the RustCrypto dependencies to the latest versions:

- `des` v0.8
- `elliptic-curve` v0.12
- `hmac` v0.12
- `num-bigint-dig` v0.8
- `pbkdf2` v0.11
- `p256` v0.11
- `p384` v0.10
- `rsa` v0.6
- `sha1` v0.10 (replacing `sha-1`)
- `sha2` v0.10

src/mgm.rs

@@ -42,7 +42,7 @@ use crate::{
     yubikey::YubiKey,
 };
 use des::{
-    cipher::{generic_array::GenericArray, BlockDecrypt, BlockEncrypt, NewBlockCipher},
+    cipher::{generic_array::GenericArray, BlockDecrypt, BlockEncrypt, KeyInit},
     TdesEde3,
 };
 #[cfg(feature = "untested")]