small fixes

lib/self-upgrade.bash

@@ -8,7 +8,7 @@
 
 function bootstrap {
   cd "$(mktemp -d)" || exit 3
-  curl -s -O $MAIN_TAR_GZ_URL
+  curl -s -O "$MAIN_TAR_GZ_URL"
   tar -xzf main.tar.gz --directory "$(dirname "$MIAOU_BASH_DIR")"
 
   local source_bin="$MIAOU_BASH_DIR/bin/miaou-bash"
@@ -39,5 +39,5 @@ latest=$("$MIAOU_BASH_DIR/tools/wget_semver" artcode miaou/miaou-bash)
 if [[ "$current" == "$latest" ]]; then
   echo "up-to-date version: $current"
 else
-  self_upgrade 
+  self_upgrade
 fi