Do not clean cache manually, new image does it automatically

Author: FloopCZ

Dockerfiles/install-archlinux.sh

@@ -20,7 +20,6 @@ done
 # install requirements
 pacman -Syu --noconfirm --needed \
   base-devel \
-  pacman-contrib \
   cmake \
   git \
   unzip \
@@ -51,8 +50,6 @@ if $cuda; then
       nccl
 fi
 
-paccache -rfk0
-
 # when building TF with Intel MKL support, `locate` database needs to exist
 updatedb