Update podspec deployment target

Kingfisher.podspec

@@ -27,10 +27,10 @@ Pod::Spec.new do |s|
 
   s.swift_versions = ['5.0']
 
-  s.ios.deployment_target = "10.0"
-  s.tvos.deployment_target = "10.0"
-  s.osx.deployment_target = "10.12"
-  s.watchos.deployment_target = "3.0"
+  s.ios.deployment_target = "12.0"
+  s.tvos.deployment_target = "12.0"
+  s.osx.deployment_target = "10.14"
+  s.watchos.deployment_target = "5.0"
 
   s.source       = { :git => "https://github.com/onevcat/Kingfisher.git", :tag => s.version }
   s.source_files  = ["Sources/**/*.swift"]