Update skype-preview to 8.8.76.60544 (#4521)

* Update skype-preview to 8.8.76.60544

* skype-preview: fixed app name

* conflicts_with cask

Casks/skype-preview.rb

@@ -1,11 +1,13 @@
 cask 'skype-preview' do
-  version '8.7.76.59440'
+  version '8.8.76.60544'
-  sha256 '269edb273e643518fdf227bfdad2e2960486d6aa41038683c3132806d361ee48'
+  sha256 '48beb93785716693ca542bfcd2c0fcaa3551b5a3a24717d56dcb794ea6c2db9f'
 
   # endpoint920510.azureedge.net/s4l/s4l/download/mac was verified as official when first introduced to the cask
-  url "https://endpoint920510.azureedge.net/s4l/s4l/download/mac/Skype-Preview-#{version}.dmg"
+  url "https://endpoint920510.azureedge.net/s4l/s4l/download/mac/Skype-#{version}.dmg"
   name 'Skype Preview'
   homepage 'https://www.skype.com/en/insider/'
 
-  app 'Skype Preview.app'
+  conflicts_with cask: 'skype'
+
+  app 'Skype.app'
 end