revert style.css to ver 5.7

vue-theme/src/sss/theme.sss

@@ -1,5 +1,5 @@
 @import url('https://fonts.googleapis.com/css?family=Crimson+Text|Questrial')
-@import url('https://c0.wp.com/c/6.0/wp-includes/css/dist/block-library/style.css')
+@import url('https://c0.wp.com/c/5.7/wp-includes/css/dist/block-library/style.css')
 
 /* Colors */
 $blue: #0076A3