Bump mock-fs from 4.10.3 to 4.10.4 (#2340)

Bumps [mock-fs](https://github.com/tschaub/mock-fs) from 4.10.3 to 4.10.4.
- [Release notes](https://github.com/tschaub/mock-fs/releases)
- [Changelog](https://github.com/tschaub/mock-fs/blob/master/changelog.md)
- [Commits](tschaub/mock-fs@v4.10.3...v4.10.4)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -61,7 +61,7 @@
     "mocha": "~5.2.0",
     "mocha-junit-reporter": "~1.23.1",
     "mocha-multi-reporters": "~1.1.7",
-    "mock-fs": "~4.10.3",
+    "mock-fs": "~4.10.4",
     "rewire": "~4.0.1",
     "sinon": "~7.5.0",
     "tslint": "~5.20.1",