[Flipper][RN] Remove the post install step

Author: priteshrnandgaonkar

scripts/react_native_pods.rb

@@ -88,14 +88,3 @@ def use_flipper!(versions = {})
   pod 'FlipperKit/FlipperKitLayoutTextSearchable', versions['Flipper'], :configuration => 'Debug'
   pod 'FlipperKit/FlipperKitNetworkPlugin', versions['Flipper'], :configuration => 'Debug'
 end
-
-# Post Install processing for Flipper
-def flipper_post_install(installer)
-  installer.pods_project.targets.each do |target|
-    if target.name == 'YogaKit'
-      target.build_configurations.each do |config|
-        config.build_settings['SWIFT_VERSION'] = '4.1'
-      end
-    end
-  end
-end