chore: upgrade webpack-dev-server to 3.4.1 (#4020)

Payton Burdette · haoqunjiang · commit 70281be0a904 · 2019-05-25T20:46:31.000+08:00
fixes #4016 (cherry picked from commit fa7c1aa)
diff --git a/packages/@vue/cli-service/package.json b/packages/@vue/cli-service/package.json
@@ -76,7 +76,7 @@
     "webpack": ">=4 < 4.29",
     "webpack-bundle-analyzer": "^3.3.0",
     "webpack-chain": "^4.11.0",
-    "webpack-dev-server": "^3.3.1",
+    "webpack-dev-server": "^3.4.1",
     "webpack-merge": "^4.2.1",
     "yorkie": "^2.0.0"
   },
