fix build failing and suppress output

Dockerfile

@@ -6,10 +6,8 @@ ARG DEBIAN_FRONTEND=noninteractive
 
 LABEL org.opencontainers.image.authors="Sebastian Sasu <[email protected]>, Cristian Magherusan-Stanciu <[email protected]>, Brooke McKim <[email protected]>"
 
-RUN apt-get update
-RUN apt-get install -y python3 pip locales
-RUN apt-get install -y nodejs
-RUN apt-get install -y npm
+RUN apt-get update > /dev/null
+RUN apt-get install -y python3 pip locales libxml2-dev libxslt-dev nodejs npm > /dev/null
 RUN npm install --global sass
 RUN python3 -m pip install -U pip setuptools
 RUN locale-gen "en_US.UTF-8"