debian/control: remove dependency on x11-utils (#3455)
debian/control: remove dependency on x11-utils (#3455)

This was a introduce in commit a61e34d2771fffdf2d94ee69d887585087c76b98 in 2009,
and we haven’t used xmessage in any way in a long time.

fixes https://bugs.debian.org/910997
i3/i3,i3/i3,Airblader/i3,stapelberg/i3,Airblader/i3-original,stapelberg/i3,i3/i3,Airblader/i3,Airblader/i3-original,Airblader/i3,Airblader/i3-original,Airblader/i3-original,i3/i3,stapelberg/i3,stapelberg/i3,Airblader/i3-original,Airblader/i3