fix(basic-image): append ^* to .drv entries to prevent warnings

instead print a "." without newline to be able to see progress

flake.nix

@@ -155,7 +155,9 @@
             '')
             (finalizeScript ''
               while read entry; do
+                [[ "$entry" == *.drv ]] && entry+="^*" || true
                 nix copy --quiet --to "file://$(pwd)/.nix-cache" $entry || true
+                echo -n "."
               done
             '')
           ];