Bump postcss-loader from 2.0.8 to 2.1.4

Bumps [postcss-loader](https://github.com/postcss/postcss-loader) from 2.0.8 to 2.1.4.
- [Release notes](https://github.com/postcss/postcss-loader/releases)
- [Changelog](https://github.com/postcss/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/postcss-loader@v2.0.8...v2.1.4)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

package-lock.json

@@ -11,7 +11,7 @@
     "eslint-plugin-react": "^7.4.0",
     "gh-pages": "^1.1.0",
     "node-sass": "^4.7.2",
-    "postcss-loader": "^2.0.8",
+    "postcss-loader": "^2.1.4",
     "prop-types": "^15.6.0",
     "resolve-url-loader": "^2.2.1",
     "sass-loader": "^6.0.6",