Update copy_lib_to_staging.sh

Allow for building on removable volumes with a space in their name, ie "/Volumes/T7 Touch/"
diff --git a/Scripts/copy_lib_to_staging.sh b/Scripts/copy_lib_to_staging.sh
index fabadd3..ff58967 100755
--- a/Scripts/copy_lib_to_staging.sh
+++ b/Scripts/copy_lib_to_staging.sh
@@ -12,4 +12,4 @@
 cp -a "${MVK_BUILT_PROD_FILE}" "${staging_dir}/${MVK_PROD_FILENAME}"
 
 # Mark the XCFrameworkStaging directory as changed, to trigger packaging dependencies.
-touch ${MVK_XCFWK_STAGING_DIR}/..
+touch "${MVK_XCFWK_STAGING_DIR}/.."