chore(deps): update dependency @types/webpack to v4

package.json

@@ -16,7 +16,7 @@
     "@typed/test": "3.6.0",
     "@types/loader-utils": "1.1.0",
     "@types/node": "8.0.28",
-    "@types/webpack": "3.0.10",
+    "@types/webpack": "4.4.4",
     "conventional-changelog-cli": "1.3.3",
     "husky": "0.14.3",
     "lint-staged": "4.2.1",

yarn.lock

@@ -152,14 +152,23 @@
   dependencies:
     "@types/source-map" "*"
 
-"@types/webpack@*", "@types/[email protected]":
+"@types/webpack@*":
   version "3.0.10"
   resolved "https://registry.yarnpkg.com/@types/webpack/-/webpack-3.0.10.tgz#1d27db07df32109f8c882535b547aae4252fd53e"
   dependencies:
     "@types/node" "*"
     "@types/tapable" "*"
     "@types/uglify-js" "*"
 
+"@types/[email protected]":
+  version "4.4.4"
+  resolved "https://registry.yarnpkg.com/@types/webpack/-/webpack-4.4.4.tgz#f001a0a43cf5b433d57a1a22366fe1939d648957"
+  dependencies:
+    "@types/node" "*"
+    "@types/tapable" "*"
+    "@types/uglify-js" "*"
+    source-map "^0.6.0"
+
 JSONStream@^1.0.4:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/JSONStream/-/JSONStream-1.3.1.tgz#707f761e01dae9e16f1bcf93703b78c70966579a"
@@ -3140,6 +3149,10 @@ source-map@^0.4.4:
   dependencies:
     amdefine ">=0.0.4"
 
+source-map@^0.6.0:
+  version "0.6.1"
+  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
+
 spdx-correct@~1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/spdx-correct/-/spdx-correct-1.0.2.tgz#4b3073d933ff51f3912f03ac5519498a4150db40"