Update postcss-cli to v6.1.1.

package-lock.json

@@ -7523,9 +7523,9 @@
       }
     },
     "postcss-cli": {
-      "version": "6.1.0",
-      "resolved": "https://registry.npmjs.org/postcss-cli/-/postcss-cli-6.1.0.tgz",
-      "integrity": "sha512-qXufMvDOvD0fvcnDYO6Rz85nSmXjIDpx2IP8CzrGv8RxAfxx5Zjvfx1GGXxbOyk8terq1Q1O8GL4ZTzBuZ1TYg==",
+      "version": "6.1.1",
+      "resolved": "https://registry.npmjs.org/postcss-cli/-/postcss-cli-6.1.1.tgz",
+      "integrity": "sha512-18PQO4qCDWY6vggnG3k+i5zrUnRc4I6P4MpKQWGbNyTfWBaRgu/nScunw6VH5QnUKtRu0NuPF5SpxhcYzWVXDg==",
       "dev": true,
       "requires": {
         "chalk": "^2.1.0",

package.json

@@ -133,7 +133,7 @@
     "nodemon": "^1.18.9",
     "npm-run-all": "^4.1.5",
     "popper.js": "^1.14.6",
-    "postcss-cli": "^6.1.0",
+    "postcss-cli": "^6.1.1",
     "qunit": "^2.8.0",
     "rollup": "^1.0.1",
     "rollup-plugin-babel": "^4.2.0",