switchhosts: add livecheck (#97639)

Casks/switchhosts.rb

@@ -4,11 +4,15 @@ cask "switchhosts" do
 
   url "https://github.com/oldj/SwitchHosts/releases/download/v#{version.major_minor_patch}/SwitchHosts._macOS_#{version}.dmg",
       verified: "github.com/oldj/SwitchHosts/"
-  appcast "https://github.com/oldj/SwitchHosts/releases.atom",
-          must_contain: version.major_minor_patch
   name "SwitchHosts!"
   desc "App to switch hosts"
   homepage "https://oldj.github.io/SwitchHosts/"
 
+  livecheck do
+    url :url
+    strategy :github_latest
+    regex(%r{/SwitchHosts\._macOS_(\d+(?:\.\d+)*)\.dmg}i)
+  end
+
   app "SwitchHosts!.app"
 end