Update exclude file in podspec

Kingfisher.podspec

@@ -36,11 +36,12 @@ Pod::Spec.new do |s|
   s.public_header_files = ["Sources/Kingfisher.h"]
   
   s.osx.exclude_files = ["Sources/AnimatedImageView.swift", "Sources/UIButton+Kingfisher.swift"]
-  s.watchos.exclude_files = ["Sources/AnimatedImageView.swift", "Sources/UIButton+Kingfisher.swift", "Sources/ImageView+Kingfisher.swift", "Sources/NSButton+Kingfisher.swift"]
+  s.watchos.exclude_files = ["Sources/AnimatedImageView.swift", "Sources/UIButton+Kingfisher.swift", "Sources/ImageView+Kingfisher.swift", "Sources/NSButton+Kingfisher.swift", "Sources/Indicator.swift"]
   s.ios.exclude_files = "Sources/NSButton+Kingfisher.swift"
   s.tvos.exclude_files = "Sources/NSButton+Kingfisher.swift"
   
   s.requires_arc = true
   s.framework = "CFNetwork"
 
+  s.pod_target_xcconfig = { 'SWIFT_VERSION' => '2.3' }
 end