Update SnapKit.podspec

* Tag 5.7.1

SnapKit.podspec

@@ -1,12 +1,12 @@
 Pod::Spec.new do |s|
   s.name = 'SnapKit'
-  s.version = '5.7.0'
+  s.version = '5.7.1'
   s.license = 'MIT'
   s.summary = 'Harness the power of auto layout with a simplified, chainable, and compile time safe syntax.'
   s.homepage = 'https://github.com/SnapKit/SnapKit'
   s.authors = { 'Robert Payne' => 'robertpayne@me.com' }
   s.social_media_url = 'http://twitter.com/robertjpayne'
-  s.source = { :git => 'https://github.com/SnapKit/SnapKit.git', :tag => '5.7.0' }
+  s.source = { :git => 'https://github.com/SnapKit/SnapKit.git', :tag => '5.7.1' }
 
   s.ios.deployment_target = '12.0'
   s.osx.deployment_target = '10.13'