build(deps): bump secp256k1 from 0.20.1 to 0.20.2

Bumps [secp256k1](https://github.com/rust-bitcoin/rust-secp256k1) from 0.20.1 to 0.20.2.
- [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

@@ -3022,9 +3022,9 @@ dependencies = [
 
 [[package]]
 name = "secp256k1"
-version = "0.20.1"
+version = "0.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "733b114f058f260c0af7591434eef4272ae1a8ec2751766d3cb89c6df8d5e450"
+checksum = "ee5070fdc6f26ca5be6dcfc3d07c76fdb974a63a8b246b459854274145f5a258"
 dependencies = [
  "secp256k1-sys",
  "serde",

zebra-chain/Cargo.toml

@@ -37,7 +37,7 @@ lazy_static = "1.4.0"
 primitive-types = "0.9.0"
 rand_core = "0.6"
 ripemd160 = "0.9"
-secp256k1 = { version = "0.20.1", features = ["serde"] }
+secp256k1 = { version = "0.20.2", features = ["serde"] }
 serde = { version = "1", features = ["serde_derive", "rc"] }
 serde-big-array = "0.3.2"
 sha2 = { version = "0.9.3", features=["compress"] }