Bump csstree to 1.1.1

Author: lahmatiy

package-lock.json

@@ -7,7 +7,7 @@
     "devDependencies": {
         "@discoveryjs/discovery": "1.0.0-beta.51",
         "@discoveryjs/cli": "^1.15.0",
-        "css-tree": "^1.1.0",
+        "css-tree": "^1.1.1",
         "diff": "^4.0.1",
         "eslint": "^7.0.0",
         "resolve": "^1.5.0"