Fix syntax

Dockerfile

@@ -263,7 +263,7 @@ ARG NOVNC_VERSION=1.5.0
 # Install Xvfb
 RUN apt-get update && apt-get install --no-install-recommends -y \
         xvfb && \
-    apt-get clean && rm -rf /var/lib/apt/lists/* /var/cache/debconf/* /var/log/* /tmp/* /var/tmp/* && \
+    apt-get clean && rm -rf /var/lib/apt/lists/* /var/cache/debconf/* /var/log/* /tmp/* /var/tmp/*
 
 # Install VirtualGL and make libraries available for preload
 RUN cd /tmp && VIRTUALGL_VERSION="$(curl -fsSL "https://api.github.com/repos/VirtualGL/virtualgl/releases/latest" | jq -r '.tag_name' | sed 's/[^0-9\.\-]*//g')" && \