update bigint 4.0

Author: TonioMacaronio

Cartfile

@@ -1,4 +1,4 @@
 github "mxcl/PromiseKit" ~> 6.8.4
-github "attaswift/BigInt" ~> 3.1
+github "attaswift/BigInt" ~> 4.0
 github "daltoniam/Starscream" ~> 3.1.0
 github "krzyzanowskim/CryptoSwift" ~> 1.0.0

Web3swift.pod.podspec

@@ -13,7 +13,7 @@ Pod::Spec.new do |spec|
     spec.module_name = 'web3swift'
     spec.frameworks = 'CoreImage'
     spec.dependency 'PromiseKit', '~> 6.8.4'
-    spec.dependency 'BigInt', '~> 3.1'
+    spec.dependency 'BigInt', '~> 4.0'
     spec.dependency 'Starscream', '~> 3.1.0'
     spec.dependency 'CryptoSwift', '~> 1.0.0'
     spec.dependency 'secp256k1.c', '~> 0.1'

web3swift.podspec

@@ -12,7 +12,7 @@ Pod::Spec.new do |spec|
     spec.swift_version = '5.0'
     spec.frameworks = 'CoreImage'
     spec.dependency 'PromiseKit', '~> 6.8.4'
-    spec.dependency 'BigInt', '~> 3.1'
+    spec.dependency 'BigInt', '~> 4.0'
     spec.dependency 'Starscream', '~> 3.1.0'
     spec.dependency 'CryptoSwift', '~> 1.0.0'
     spec.dependency 'secp256k1.c', '~> 0.1'