Merge pull request #6 from lishuailibertine/master

update Secp256k1Swift 2.0.0

Author: yuzhiyou1990

Package.swift

@@ -18,7 +18,7 @@ let package = Package(
         // Dependencies declare other packages that this package depends on.
          .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.18.0"),
          .package(url: "https://github.com/krzyzanowskim/CryptoSwift.git", from: "1.4.2"),
-         .package(url: "https://github.com/mathwallet/Secp256k1Swift.git", from: "1.3.1"),
+         .package(url: "https://github.com/mathwallet/Secp256k1Swift.git", from: "2.0.0"),
          .package(url: "https://github.com/mxcl/PromiseKit.git", from: "6.16.2")
     ],
     targets: [