chore(dependencies): Bump webpack from 3.8.1 to 3.9.1 (#43)

Bumps [webpack](https:/webpack/webpack) from 3.8.1 to 3.9.1.
- [Release notes](https:/webpack/webpack/releases)
- [Commits](webpack/webpack@v3.8.1...v3.9.1)

package.json

@@ -60,7 +60,7 @@
  "sinon": "^4.1.2",
  "standard-changelog": "^1.0.5",
  "standard-version": "^4.2.0",
- "webpack": "^3.5.4",
+ "webpack": "^3.9.1",
  "webpack-dev-server": "^2.9.5"
  },
  "peerDependencies": {

yarn.lock

@@ -5501,9 +5501,9 @@ webpack-sources@^1.0.1:
  source-list-map "^2.0.0"
  source-map "~0.6.1"
 
-webpack@^3.5.4:
- version "3.8.1"
- resolved "https://registry.yarnpkg.com/webpack/-/webpack-3.8.1.tgz#b16968a81100abe61608b0153c9159ef8bb2bd83"
+webpack@^3.9.1:
+ version "3.9.1"
+ resolved "https://registry.yarnpkg.com/webpack/-/webpack-3.9.1.tgz#9a60aa544ed5d4d454c069e3f521aa007e02643c"
  dependencies:
  acorn "^5.0.0"
  acorn-dynamic-import "^2.0.0"