ecdsa: remove TryFrom/TryInto imports (#454) (#386)

Now that we've upgraded to Rust 2021 edition, these are now available
via the prelude, making explicit imports redundant.

ecdsa/src/der.rs

@@ -2,7 +2,6 @@
 
 use crate::{Error, Result};
 use core::{
-    convert::{TryFrom, TryInto},
     fmt,
     ops::{Add, Range},
 };

ecdsa/src/dev.rs

@@ -32,7 +32,6 @@ pub struct TestVector {
 #[cfg_attr(docsrs, doc(cfg(feature = "dev")))]
 macro_rules! new_signing_test {
     ($curve:path, $vectors:expr) => {
-        use core::convert::TryInto;
         use $crate::{
             elliptic_curve::{
                 bigint::Encoding, generic_array::GenericArray, group::ff::PrimeField, Curve,
@@ -69,7 +68,6 @@ macro_rules! new_signing_test {
 #[cfg_attr(docsrs, doc(cfg(feature = "dev")))]
 macro_rules! new_verification_test {
     ($curve:path, $vectors:expr) => {
-        use core::convert::TryInto;
         use $crate::{
             elliptic_curve::{
                 generic_array::GenericArray,

ecdsa/src/lib.rs

@@ -92,7 +92,6 @@ pub use sign::SigningKey;
 pub use verify::VerifyingKey;
 
 use core::{
-    convert::TryFrom,
     fmt::{self, Debug},
     ops::Add,
 };

ecdsa/src/sign.rs

@@ -6,10 +6,7 @@ use crate::{
     hazmat::{DigestPrimitive, SignPrimitive},
     rfc6979, Error, Result, Signature, SignatureSize,
 };
-use core::{
-    convert::TryFrom,
-    fmt::{self, Debug},
-};
+use core::fmt::{self, Debug};
 use elliptic_curve::{
     generic_array::ArrayLength,
     group::ff::PrimeField,

ecdsa/src/verify.rs

@@ -4,7 +4,7 @@ use crate::{
     hazmat::{DigestPrimitive, VerifyPrimitive},
     Error, Result, Signature, SignatureSize,
 };
-use core::{cmp::Ordering, convert::TryFrom, fmt::Debug};
+use core::{cmp::Ordering, fmt::Debug};
 use elliptic_curve::{
     generic_array::ArrayLength,
     ops::Reduce,

ecdsa/tests/lib.rs

@@ -2,7 +2,6 @@
 
 #![cfg(feature = "dev")]
 
-use core::convert::TryFrom;
 use elliptic_curve::dev::MockCurve;
 
 type Signature = ecdsa::Signature<MockCurve>;