Update dependency webpack-cli to v3.3.8

Author: renovate-bot

fixtures/app/package.json

@@ -13,6 +13,6 @@
   },
   "devDependencies": {
     "webpack": "4.20.2",
-    "webpack-cli": "3.2.1"
+    "webpack-cli": "3.3.8"
   }
 }

fixtures/subdep/package.json

@@ -8,6 +8,6 @@
   },
   "devDependencies": {
     "webpack": "4.20.2",
-    "webpack-cli": "3.2.1"
+    "webpack-cli": "3.3.8"
   }
 }

worker/package.json

@@ -13,7 +13,7 @@
     "css-to-js-sourcemap-core": "*",
     "resolve-from": "4.0.0",
     "webpack": "4.20.2",
-    "webpack-cli": "3.2.1"
+    "webpack-cli": "3.3.8"
   },
   "license": "MIT"
 }