migrate to Swift 4.2

PerspectiveTransform.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
   s.cocoapods_version = '~> 1.5'
   s.name              = 'PerspectiveTransform'
-  s.version           = '0.3.4'
+  s.version           = '0.4'
   s.summary           = 'Perspective Transform calculates CATransform3D'
   s.description       = <<-DESC
   Calculates CATransform3D to transform rectangular frame to convex quadrilateral
@@ -14,7 +14,7 @@ Pod::Spec.new do |s|
   s.author            = { 'Paul Zabelin' => authorPage }
   s.source            = { :git => "#{s.homepage}.git", :tag => s.version.to_s }
   s.social_media_url  = 'https://twitter.com/iospaulz'
-  s.platform          = :ios, '8.0'
+  s.platform          = :ios, '11.0'
   s.swift_version     = '4.2'
   s.source_files      = 'Pod/Classes/**/*'
   s.frameworks        = 'UIKit', 'CoreGraphics', 'QuartzCore'
@@ -31,8 +31,8 @@ Pod::Spec.new do |s|
       ts.source_files   = 'Example/Tests/**/*.{h,swift}', 'Example/PerspectiveTransform/resetAnchorPoint.swift'
       ts.dependencies   = {
           'Quick' => '~> 1.3',
-          'Nimble-Snapshots' => '~> 6.7',
-          'iOSSnapshotTestCase' => '~> 3.0'
+          'Nimble-Snapshots' => '~> 6.8',
+          'iOSSnapshotTestCase' => '~> 4.0'
       }
   end
 end