Bump memfs from 4.7.1 to 4.7.7

Bumps [memfs](https://github.com/streamich/memfs) from 4.7.1 to 4.7.7.
- [Release notes](https://github.com/streamich/memfs/releases)
- [Changelog](https://github.com/streamich/memfs/blob/master/CHANGELOG.md)
- [Commits](streamich/memfs@v4.7.1...v4.7.7)

---
updated-dependencies:
- dependency-name: memfs
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

package-lock.json

@@ -99,7 +99,7 @@
     "markdown": "^0.5.0",
     "mathjax-full": "^3.2.2",
     "mdn-data": "^2.4.2",
-    "memfs": "^4.7.1",
+    "memfs": "^4.7.7",
     "mhchemparser": "^4.2.1",
     "minimist": "^1.2.8",
     "mj-context-menu": "^0.9.1",