Use container for MC deb download

installJRMC

@@ -1842,7 +1842,7 @@ apt_mc_container() {
   declare -g CNT
   install_package --silent buildah &>/dev/null && 
   CNT=$(sudo buildah from --quiet alpine:edge 2>/dev/null) &&
-  sudo buildah run "$cnt" -- sh -c '
+  sudo buildah run "$CNT" -- sh -c '
     apk add --no-cache apt curl gnupg &>/dev/null
     curl -fsSL https://dist.jriver.com/mediacenter@jriver.com.gpg.key | gpg --dearmor -o /usr/share/keyrings/jriver-com-archive-keyring.gpg &>/dev/null
     cat <<-EOF > /etc/apt/sources.list.d/jriver.sources