Bump elliptic-curve to v0.10; MSRV 1.51+ (#268)

Also updates the following:
- `p256` v0.9
- `p384` v0.8

tests/integration.rs

@@ -8,8 +8,11 @@ use lazy_static::lazy_static;
 use log::trace;
 use rsa::{hash::Hash::SHA2_256, PaddingScheme, PublicKey};
 use sha2::{Digest, Sha256};
-use std::convert::TryInto;
-use std::{env, sync::Mutex};
+use std::{
+    convert::{TryFrom, TryInto},
+    env,
+    sync::Mutex,
+};
 use x509::RelativeDistinguishedName;
 use yubikey::{
     certificate::{Certificate, PublicKeyInfo},
@@ -240,9 +243,9 @@ fn generate_self_signed_ec_cert() {
     let sig_algo_len = data[7 + tbs_cert_len + 1] as usize;
     let sig_start = 7 + tbs_cert_len + 2 + sig_algo_len + 3;
     let msg = &data[4..7 + tbs_cert_len];
-    let sig = &data[sig_start..];
+    let sig = p256::ecdsa::Signature::try_from(&data[sig_start..]).unwrap();
+    let vk = p256::ecdsa::VerifyingKey::from_sec1_bytes(pubkey.as_bytes()).unwrap();
 
-    use ring::signature::{UnparsedPublicKey, ECDSA_P256_SHA256_ASN1};
-    let ring_pk = UnparsedPublicKey::new(&ECDSA_P256_SHA256_ASN1, pubkey.as_bytes());
-    assert!(ring_pk.verify(msg, sig).is_ok());
+    use p256::ecdsa::signature::Verifier;
+    assert!(vk.verify(msg, &sig).is_ok());
 }