Adding MATE themes

Dockerfile

@@ -265,6 +265,7 @@ RUN dpkg --add-architecture i386 \
         xserver-xorg-input-libinput \
         xserver-xorg-legacy \
         xz-utils \
+        mate-themes \
     && sed -i \
         -e 's/^# *fr_FR.UTF-8 UTF-8/fr_FR.UTF-8 UTF-8/' \
         -e 's/^# *en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' \