drop-to-gif: add livecheck (#102365)

Casks/drop-to-gif.rb

@@ -4,7 +4,6 @@ cask "drop-to-gif" do
 
   url "https://github.com/mortenjust/droptogif/releases/download/#{version}/Drop.to.GIF#{version.no_dots}.zip",
       verified: "github.com/mortenjust/droptogif/"
-  appcast "https://github.com/mortenjust/droptogif/releases.atom"
   name "Drop to GIF"
   desc "Zero-click animated Gifs"
   homepage "https://mortenjust.github.io/droptogif/"

audit_exceptions/github_prerelease_allowlist.json

@@ -4,6 +4,7 @@
   "cleartext": "all",
   "comma-chameleon": "all",
   "crypter": "all",
+  "drop-to-gif": "all",
   "duplicati": "all",
   "extraterm": "all",
   "freetube": "all",