Greenkeeper/autoprefixer 9.4.2 (#2382)

* chore(package): update autoprefixer to version 9.4.2

* chore(package): update lockfile package-lock.json

Author: mgechev

package-lock.json

@@ -79,7 +79,7 @@
     "@types/yargs": "12.0.0",
     "ansi-colors": "^3.0.6",
     "async": "^2.6.1",
-    "autoprefixer": "^9.1.1",
+    "autoprefixer": "^9.4.2",
     "browser-sync": "^2.24.6",
     "browserslist": "^4.0.2",
     "codelyzer": "^4.4.4",