update dependencies

package.json

@@ -28,9 +28,9 @@
     "@babel/plugin-transform-runtime": "^7.1.0",
     "@babel/preset-env": "^7.1.0",
     "@babel/runtime": "^7.1.2",
-    "autoprefixer": "^9.2.1",
+    "autoprefixer": "^9.3.1",
     "cross-env": "^5.2.0",
-    "cssnano": "^4.1.4",
+    "cssnano": "^4.1.7",
     "node-sass": "^4.9.4",
     "rollup": "^0.66.6",
     "rollup-plugin-babel": "^4.0.3",