Bump webpack from 5.0.0-beta.16 to 5.0.0-beta.18

Bumps [webpack](https://github.com/webpack/webpack) from 5.0.0-beta.16 to 5.0.0-beta.18.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](https://github.com/webpack/webpack/compare/v5.0.0-beta.16...v5.0.0-beta.18)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -50,7 +50,7 @@
     "typescript": "^3.9.3",
     "url-loader": "^3.0.0",
     "val-loader": "2.1.1",
-    "webpack": "^5.0.0-beta.16",
+    "webpack": "^5.0.0-beta.18",
     "webpack-cli": "^3.3.10",
     "yaml-loader": "0.6.0"
   },