upload-appimage.sh correction

Signed-off-by: Thatoo <thatoo@users.noreply.github.com>

admin/linux/upload-appimage.sh

@@ -24,7 +24,7 @@ cd /build
 
 # AppImage
 export APPIMAGE=$(readlink -f ./Nextcloud*.AppImage)
-export UPDATE==$(readlink -f ./Nextcloud*.AppImage.zsync)
+export UPDATE=$(readlink -f ./Nextcloud*.AppImage.zsync)
 export BASENAME=$(basename ${APPIMAGE})
 
 if ! test -e $APPIMAGE ; then