Upgrade postcss6

TrySound · TrySound · commit 686cb25e1fd6 · 2017-05-20T22:43:29.000+03:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,9 +1,8 @@
-sudo: false
 language: node_js
 node_js:
-  - 4
-  - 6
-  - 7
+  - "4"
+  - "6"
+  - "node"
 script: npm run travis
 
 after_success:
diff --git a/package.json b/package.json
@@ -16,7 +16,7 @@
   },
   "dependencies": {
     "css-selector-tokenizer": "^0.7.0",
-    "postcss": "^5.0.4"
+    "postcss": "^6.0.1"
   },
   "devDependencies": {
     "chokidar-cli": "^1.0.1",
