fix: upgrade @adobe/css-tools to 4.3.1 to address vulnerability (#532)

Author: justinbaltazar

package.json

@@ -80,7 +80,7 @@
   "author": "Ernesto Garcia <[email protected]> (http://gnapse.github.io)",
   "license": "MIT",
   "dependencies": {
-    "@adobe/css-tools": "^4.3.0",
+    "@adobe/css-tools": "^4.3.1",
     "@babel/runtime": "^7.9.2",
     "aria-query": "^5.0.0",
     "chalk": "^3.0.0",