Bump core-js from 3.20.3 to 3.21.0 (#349)

Bumps [core-js](https://github.com/zloirock/core-js) from 3.20.3 to 3.21.0.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](zloirock/core-js@v3.20.3...v3.21.0)

---
updated-dependencies:
- dependency-name: core-js
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -34,7 +34,7 @@
     "workbox-cli": "^6.4.2"
   },
   "dependencies": {
-    "core-js": "^3.20.3",
+    "core-js": "^3.21.0",
     "d3-array": "^3.1.1",
     "d3-scale": "^4.0.2",
     "d3-shape": "^3.1.0",