Modernize sources list for containerized package manager

installJRMC

@@ -434,16 +434,14 @@ get_latest_mc_version() {
   # Use generalized containerized package manager to determine latest MC version
   if install_package --silent buildah && 
   cnt=$(buildah from --quiet alpine:edge 2>/dev/null) &&
-  buildah run "$cnt" -- sh -c "apk add apt" &>/dev/null &&
-  buildah run "$cnt" -- sh -c \
-    'cat <<-EOF > /etc/apt/sources.list.d/dist.jriver.com.sources
-			Types: deb
-			URIs: https://dist.jriver.com/latest/mediacenter/
-			Suites: '"$1"'
-			Components: main
-		EOF' &&
-  buildah run "$cnt" -- sh -c \
-    "apt update --allow-insecure-repositories" &&
+buildah run "$cnt" -- sh -c "apk add apt &>/dev/null &&
+cat <<-EOF > /etc/apt/sources.list.d/dist.jriver.com.sources
+    Types: deb
+    URIs: https://dist.jriver.com/latest/mediacenter/
+    Suites: $1
+    Components: main
+EOF
+&& apt update --allow-insecure-repositories" &&
   MC_VERSION=$(buildah run "$cnt" -- apt-cache policy mediacenter?? | grep Candidate | awk '{print $2}' | sort -V | tail -n1) &>/dev/null &&
   [[ $MC_VERSION =~ ^[0-9]+\.[0-9]+\.[0-9]+ ]]; then
     mc_version_source="containerized package manager"