vscodium: add livecheck

By default, livecheck checks the Git tags for `vscodium` and it
correctly returns 1.89.1.24130 as the latest version but the releases
after 1.88.1.24104 haven't provided assets for macOS because of a
temporary technical issue.

This adds a `GithubReleases` `livecheck` block to restrict matching
to releases with dmg files. We should be able to switch to
`strategy :github_latest` once upstream provides dmg files in
subsequent releases but this addresses the issue for the moment.

Casks/v/vscodium.rb

@@ -10,6 +10,27 @@
   desc "Binary releases of VS Code without MS branding/telemetry/licensing"
   homepage "https://github.com/VSCodium/vscodium"
 
+  # Not every GitHub release provides a file for macOS, so we check multiple
+  # recent releases instead of only the "latest" release. NOTE: We should be
+  # able to use `strategy :github_latest` when subsequent releases provide
+  # files for macOS again.
+  livecheck do
+    url :url
+    regex(/^VScodium[._-]#{arch}[._-]v?(\d+(?:\.\d+)+)\.(?:dmg|pkg)$/i)
+    strategy :github_releases do |json, regex|
+      json.map do |release|
+        next if release["draft"] || release["prerelease"]
+
+        release["assets"]&.map do |asset|
+          match = asset["name"]&.match(regex)
+          next if match.blank?
+
+          match[1]
+        end
+      end.flatten
+    end
+  end
+
   auto_updates true
   depends_on macos: ">= :high_sierra"