fix: postcss-loader warnings (close: #278)

Author: ulivz

package.json

@@ -72,7 +72,7 @@
     "object-assign": "^4.1.1",
     "optimize-css-assets-webpack-plugin": "^4.0.0",
     "portfinder": "^1.0.13",
-    "postcss-loader": "^2.1.3",
+    "postcss-loader": "^2.1.5",
     "prismjs": "^1.13.0",
     "register-service-worker": "^1.2.0",
     "semver": "^5.5.0",

yarn.lock

@@ -4872,9 +4872,9 @@ postcss-load-plugins@^2.3.0:
     cosmiconfig "^2.1.1"
     object-assign "^4.1.0"
 
-postcss-loader@^2.1.3:
-  version "2.1.4"
-  resolved "https://registry.yarnpkg.com/postcss-loader/-/postcss-loader-2.1.4.tgz#f44a6390e03c84108b2b2063182d1a1011b2ce76"
+postcss-loader@^2.1.5:
+  version "2.1.5"
+  resolved "https://registry.yarnpkg.com/postcss-loader/-/postcss-loader-2.1.5.tgz#3c6336ee641c8f95138172533ae461a83595e788"
   dependencies:
     loader-utils "^1.1.0"
     postcss "^6.0.0"