Do not run anymore on Debian Buster (libgconf2-4 lib no more available)

[regis-allais]

Since Debian Buster 10 version : obsolete libgconf2-4 has been replaced by gconf-gsettings-backend

[astoilkov]

This a problem that can sometimes be fixed. Can you check the suggestions in the issues below and let me know if it helps:

• https://github.com/careteditor/issues/issues/578
• https://github.com/careteditor/releases-beta/issues/5