Bump karma-sourcemap-loader from 0.3.8 to 0.4.0

Bumps [karma-sourcemap-loader](https://github.com/demerzel3/karma-sourcemap-loader) from 0.3.8 to 0.4.0.
- [Changelog](https://github.com/demerzel3/karma-sourcemap-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/demerzel3/karma-sourcemap-loader/commits/0.4.0)

---
updated-dependencies:
- dependency-name: karma-sourcemap-loader
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -38,7 +38,7 @@
     "karma-mocha": "^2.0.1",
     "karma-phantomjs-launcher": "^1.0.0",
     "karma-sinon": "^1.0.4",
-    "karma-sourcemap-loader": "^0.3.8",
+    "karma-sourcemap-loader": "^0.4.0",
     "karma-webpack": "^5.0.1",
     "mocha": "^8.2.1",
     "mocha-webpack": "^1.1.0",