build(deps): bump secp256k1 from 0.19.0 to 0.20.0

Bumps [secp256k1](https://github.com/rust-bitcoin/rust-secp256k1) from 0.19.0 to 0.20.0.
- [Release notes](https://github.com/rust-bitcoin/rust-secp256k1/releases)
- [Changelog](https://github.com/rust-bitcoin/rust-secp256k1/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-bitcoin/rust-secp256k1/commits)

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -2638,9 +2638,9 @@ dependencies = [
 
 [[package]]
 name = "secp256k1"
-version = "0.19.0"
+version = "0.20.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c6179428c22c73ac0fbb7b5579a56353ce78ba29759b3b8575183336ea74cdfb"
+checksum = "fcfd0eece5bc8fca7ca07a0c17ffd334b028f72ffbe9dd8ec924a8c885753278"
 dependencies = [
  "secp256k1-sys",
  "serde",
@@ -2648,9 +2648,9 @@ dependencies = [
 
 [[package]]
 name = "secp256k1-sys"
-version = "0.3.0"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "11553d210db090930f4432bea123b31f70bbf693ace14504ea2a35e796c28dd2"
+checksum = "67e4b6455ee49f5901c8985b88f98fb0a0e1d90a6661f5a03f4888bd987dad29"
 dependencies = [
  "cc",
 ]

zebra-chain/Cargo.toml

@@ -27,7 +27,7 @@ lazy_static = "1.4.0"
 primitive-types = "0.7.3"
 rand_core = "0.5.1"
 ripemd160 = "0.8.0"
-secp256k1 = { version = "0.19.0", features = ["serde"] }
+secp256k1 = { version = "0.20.0", features = ["serde"] }
 serde = { version = "1", features = ["serde_derive", "rc"] }
 serde-big-array = "0.3.1"
 sha2 = { version = "0.9.2", features=["compress"] }