remove unused variable in BIP32 keystore

Author: Alex Vlasov

web3swift.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
 s.name             = "web3swift"
-s.version          = "0.6.0"
+s.version          = "0.7.0"
 s.summary          = "Web3 implementation in vanilla Swift for iOS ans macOS"
 
 s.description      = <<-DESC

web3swift/KeystoreManager/Classes/BIP32Keystore.swift

@@ -45,7 +45,7 @@ public class BIP32Keystore: AbstractKeystore {
     // --------------
 
     public var keystoreParams: KeystoreParamsBIP32?
-    public var mnemonics: String?
+//    public var mnemonics: String?
     public var paths: [String:EthereumAddress] = [String:EthereumAddress]()
     public var rootPrefix: String
     public convenience init?(_ jsonString: String) {