Update airmail-beta to 3.0.2.387,267 (#2674)

Casks/airmail-beta.rb

@@ -1,11 +1,11 @@
 cask 'airmail-beta' do
-  version '3.0.2.386,266'
-  sha256 'de585cd058bf9f00a208db51b91ffbf65450b86ce085b5ea4b783bbfb8e0aa32'
+  version '3.0.2.387,267'
+  sha256 '54075c15b1a91d2197655c79f00d08d2b45a47900a6c8af2beddf6c22e70b3b9'
 
   # hockeyapp.net/api/2/apps/84be85c3331ee1d222fd7f0b59e41b04 was verified as official when first introduced to the cask
   url "https://rink.hockeyapp.net/api/2/apps/84be85c3331ee1d222fd7f0b59e41b04/app_versions/#{version.after_comma}?format=zip&"
   appcast 'https://rink.hockeyapp.net/api/2/apps/84be85c3331ee1d222fd7f0b59e41b04',
-          checkpoint: '5ecac942573de0e515764ff66406d9da148c65222ab7c31a7ff87f744cc37234'
+          checkpoint: '999d39f13813ccf68f59df00a134e13e133816d88862df104089eef814d7dbb0'
   name 'Airmail'
   homepage 'http://airmailapp.com/beta/'
   license :commercial