Update postcss-import to v8.1.2 from v7.1.0

Author: watilde

package.json

@@ -31,7 +31,7 @@
   },
   "devDependencies": {
     "jshint": "^2.9.2",
-    "postcss-import": "^7.1.0",
+    "postcss-import": "^8.1.2",
     "postcss-url": "^5.1.2"
   }
 }