chore(package): update postcss to version 6.0.22

Author: greenkeeper[bot]

package.json

@@ -90,7 +90,7 @@
     "lodash": "4.17.5",
     "ngx-combination-generator": "^1.0.2",
     "node-sass": "4.9.0",
-    "postcss": "6.0.21",
+    "postcss": "6.0.22",
     "postcss-strip-inline-comments": "0.1.5",
     "pump": "3.0.0",
     "raw-loader": "0.5.1",