fix problematic echos

scripts/update-git-keys.nix

@@ -46,7 +46,7 @@ writers.writeBashBin "update-git-keys" ''
   # declare -p curl_common
   echo GET "$url_keys"
   resp="$("''${curl_common[@]}" "$url_keys")"
-  for url in $(echo "$resp" | jq .[].url -r); do
+  for url in $(printf '%s' "$resp" | jq .[].url -r); do
     echo DELETE "$url"
     "''${curl_common[@]}" "$url" -X DELETE
   done