Revert "apple: add skyemu core to app store build"

This reverts commit 5176452.

Temporarily revert until ios/tvos build of skyemu only contain correct
architectures, skylersaleh/SkyEmu#550

Author: warmenhoven

pkg/apple/update-cores.sh

@@ -262,7 +262,6 @@ appstore_cores=(
     sameboy
     sameduck
     scummvm
-    skyemu
     smsplus
     snes9x
     snes9x2005