wavtap: add livecheck (#102551)

Casks/wavtap.rb

@@ -3,7 +3,6 @@ cask "wavtap" do
   sha256 "b114703e407ce269070165421a81f74e64ac1730a85d829c148325b4ac1a18f6"
 
   url "https://github.com/pje/WavTap/releases/download/#{version}/WavTap.#{version}.pkg"
-  appcast "https://github.com/pje/WavTap/releases.atom"
   name "WavTap"
   desc "Tool to globally capture whatever sound is playing"
   homepage "https://github.com/pje/wavtap"
@@ -12,4 +11,8 @@ cask "wavtap" do
 
   uninstall pkgutil: "com.wavtap.*",
             kext:    "com.wavtap.driver.WavTap"
+
+  caveats do
+    discontinued
+  end
 end