There is a tweak to make the application compatible with the version, but be advised that Skype will give you errors since it's using additional technologies in newer versions.
Right click Skype and select Show Package Contents, then double click the Info.plist and open it with the text editor. Scroll down until you see these lines:
The numbers might be different, but replace it with the following one: 18.104.22.1687. Close the file, save the package, and relaunch Skype. It should work now.