Update + validate podspec

ARVideoKit.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = "ARVideoKit"
-  s.version      = "1.3"
+  s.version      = "1.51"
   s.summary      = "Capture & record ARKit videos 📹, photos 🌄, Live Photos 🎇, and GIFs 🎆."
   s.description  = "Enabling developers to capture videos 📹, photos 🌄, Live Photos 🎇, and GIFs 🎆 with augmented reality components."
   s.homepage     = "https://github.com/AFathi/ARVideoKit"
@@ -16,7 +16,8 @@ Pod::Spec.new do |s|
 
   s.platform     = :ios, "11.0"
 
-  s.source       = { :git => "https://github.com/AFathi/ARVideoKit.git", :tag => "1.3" }
+  # ARVideoKit for Swift 4.2
+  s.source       = { :git => "https://github.com/AFathi/ARVideoKit.git", :tag => "1.51" }
   s.source_files  = "ARVideoKit", "ARVideoKit/**/*.{h,m,swift}"
   s.resources = "ARVideoKit/Assets/*.scnassets"
 end