flatpak: Fix ePub view not starting in some cases
Punch a hole in the sandbox to have access to the GPU, so that the Wayland sub-compositor in WebKitGtk can be started.
libEGL warning: wayland-egl: could not open /dev/dri/card0 (No such file or directory) WaylandCompositor requires eglCreateImage and eglDestroyImage. Nested Wayland compositor could not initialize EGL
Closes: #9 (closed)