fix s6-overlays for proper CPU arch selection (#131)

Co-authored-by: Ruslan Ponomarenko <r.ponomarenko@itoutposts.com>

Author: xriser

script/install-s6-overlay.sh

@@ -35,5 +35,4 @@ esac
 
 URL="https://github.com/just-containers/s6-overlay/releases/download/v${S6_VERSION}/s6-overlay-${ARCH}.tar.gz"
 
-curl -L -s https://github.com/just-containers/s6-overlay/releases/download/v${S6_VERSION}/s6-overlay-amd64.tar.gz \
-  | tar xzf - -C /
+curl -L -s "$URL" | tar xpzf - -C /