add tvos version

Author: michaeleisel

JJLISO8601DateFormatter.podspec

@@ -21,6 +21,7 @@ Pod::Spec.new do |s|
   s.source           = { :git => 'https://github.com/michaeleisel/JJLISO8601DateFormatter.git', :tag => s.version.to_s }
 
   s.ios.deployment_target = '11.0'
+  s.tvos.deployment_target = '11.0'
   s.osx.deployment_target = '10.13'
 
   s.source_files = 'Sources/JJLISO8601DateFormatter/**/*'