Update dependency offline-plugin to v5

package.json

@@ -28,7 +28,7 @@
     "file-loader": "0.11.2",
     "html-webpack-plugin": "2.29.0",
     "node-sass": "4.5.3",
-    "offline-plugin": "4.8.3",
+    "offline-plugin": "5.0.6",
     "sass-loader": "6.0.6",
     "style-loader": "0.18.2",
     "webpack": "3.4.1",

yarn.lock

@@ -1460,7 +1460,11 @@ deep-equal@^1.0.0, deep-equal@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/deep-equal/-/deep-equal-1.0.1.tgz#f5d260292b660e084eff4cdbc9f08ad3247448b5"
 
-deep-extend@^0.4.0, deep-extend@~0.4.0:
+deep-extend@^0.5.1:
+  version "0.5.1"
+  resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.5.1.tgz#b894a9dd90d3023fbf1c55a394fb858eb2066f1f"
+
+deep-extend@~0.4.0:
   version "0.4.2"
   resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.4.2.tgz#48b699c27e334bf89f10892be432f6e4c7d34a7f"
 
@@ -3464,11 +3468,11 @@ obuf@^1.0.0, obuf@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/obuf/-/obuf-1.1.1.tgz#104124b6c602c6796881a042541d36db43a5264e"
 
-offline-plugin@4.8.3:
-  version "4.8.3"
-  resolved "https://registry.yarnpkg.com/offline-plugin/-/offline-plugin-4.8.3.tgz#9e95bd342ea2ac836b001b81f204c40638694d6c"
+offline-plugin@5.0.6:
+  version "5.0.6"
+  resolved "https://registry.yarnpkg.com/offline-plugin/-/offline-plugin-5.0.6.tgz#7a7b244220cddb8a8cabecb172ec5c0be03e74b2"
   dependencies:
-    deep-extend "^0.4.0"
+    deep-extend "^0.5.1"
     ejs "^2.3.4"
     loader-utils "0.2.x"
     minimatch "^3.0.3"