Fix podspec

Author: muukii

StackScrollView.podspec

@@ -1,7 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'StackScrollView'
   s.version          = '1.6.3'
-  :xa
   s.summary          = 'Scalable form builder with UICollectionView'
   s.homepage         = 'https://github.com/muukii/StackScrollView'
   s.license          = { :type => 'MIT', :file => 'LICENSE' }