Bump lodash from 4.17.15 to 4.17.21 in /gui

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.15 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](lodash/lodash@4.17.15...4.17.21)

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

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

gui/package.json

@@ -31,7 +31,7 @@
     "deep-assign": "2.0.0",
     "es6-promise": "4.1.1",
     "history": "3.3.0",
-    "lodash": "4.17.15",
+    "lodash": "4.17.21",
     "napa": "2.3.0",
     "object-hash": "1.3.0",
     "prismjs": "1.15.0",