Bump webpack from 4.39.1 to 4.39.2

Bumps [webpack](https://github.com/webpack/webpack) from 4.39.1 to 4.39.2.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v4.39.1...v4.39.2)

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Author: dependabot-preview[bot]

js/viewer.js.map

@@ -79,7 +79,7 @@
     "url-loader": "^2.1.0",
     "vue-loader": "^15.7.1",
     "vue-template-compiler": "^2.6.10",
-    "webpack": "^4.39.1",
+    "webpack": "^4.39.2",
     "webpack-cli": "^3.3.6",
     "webpack-merge": "^4.2.1",
     "webpack-node-externals": "^1.7.2"