Update Sparkle to 1.20.0

Unfortunately, due to the nature of the issue a manual update to a new
version will be required.

Fixes: #600

macosx/Sparkle.framework/Versions/A/Modules/module.modulemap

@@ -0,0 +1,6 @@
+framework module Sparkle {
+  umbrella header "Sparkle.h"
+
+  export *
+  module * { export * }
+}