Bump log4js from 6.1.2 to 6.4.0

Bumps [log4js](https://github.com/log4js-node/log4js-node) from 6.1.2 to 6.4.0.
- [Release notes](https://github.com/log4js-node/log4js-node/releases)
- [Changelog](https://github.com/log4js-node/log4js-node/blob/master/CHANGELOG.md)
- [Commits](log4js-node/log4js-node@v6.1.2...v6.4.0)

---
updated-dependencies:
- dependency-name: log4js
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package-lock.json

@@ -18,7 +18,7 @@
   "dependencies": {
     "@stroncium/procfs": "^1.0.0",
     "docopt": "^0.6.2",
-    "log4js": "^6.1.0",
+    "log4js": "^6.4.0",
     "pidtree": "^0.3.0",
     "pidusage": "^2.0.18",
     "read-env": "^2.0.0",