Fix kdeconnect_open MimeType

This changes the MimeType handler of the kdeconnect_open desktop file from an invalid "*/*" to the (hopefully) appropriate "application/octet-stream;" as discussed [here](https://bugs.launchpad.net/ubuntu/+source/kdeconnect/+bug/1878400)(including this solution), [here](clearlinux/distribution#1906) and [here](https://bugs.archlinux.org/task/65865).

(cherry picked from commit f1ce221)

data/org.kde.kdeconnect_open.desktop

@@ -97,7 +97,7 @@ Comment[uk]=Відкрити на з'єднаному пристрої за до
 Comment[x-test]=xxOpen on a connected device using KDE Connectxx
 Comment[zh_CN]=通过 KDE Connect 在已连接的设备上打开
 Comment[zh_TW]=使用 KDE 連線於連線裝置中開啟
-MimeType=*/*;
+MimeType=application/octet-stream;
 Exec=kdeconnect-handler --open %U
 Icon=kdeconnect
 Type=Service