minor change

Dockerfile

@@ -7,7 +7,8 @@ ENV DEBIAN_FRONTEND noninteractive
 
 # Install GTK, pulseaudio and fonts
 RUN apt-get update && \
-    apt-get install -y libcanberra-gtk-module libexif12 pulseaudio attr \
+    apt-get -y --no-install-recommends install ca-certificates \
+                       libcanberra-gtk-module libexif12 pulseaudio attr \
                        fonts-dejavu-core fonts-freefont-ttf fonts-guru-extra \
                        fonts-kacst fonts-kacst-one fonts-khmeros-core fonts-lao \
                        fonts-liberation fonts-lklug-sinhala fonts-lohit-guru \
@@ -37,7 +38,6 @@ RUN sh -c 'dpkg -i /tmp/google-chrome-stable_current_amd64.deb \
     apt-get -fy install && \
     rm -rf -- /var/lib/apt/lists /tmp/*.deb
 
-
 # Workaround: pulseaudio client library likes to remove /dev/shm/pulse-shm-*
 #             files created by the host, causing sound to stop working.
 #             To fix this, we either want to disable the shm or mount /dev/shm