entry: update livecheck

Casks/e/entry.rb

@@ -7,8 +7,12 @@ cask "entry" do
   desc "Block-based coding platform"
   homepage "https://playentry.org/"
 
+  # The download page (https://playentry.org/download/offline) fetches the
+  # version information from https://playentry.org/graphql using a `POST`
+  # request but livecheck can't do that yet. We check GitHub releases as a best
+  # guess of when a new version is released.
   livecheck do
-    url "https://github.com/entrylabs/entry-offline/"
+    url "https://github.com/entrylabs/entry-offline"
     strategy :github_latest
   end