Bump firebase from 8.6.2 to 8.9.1

Bumps [firebase](https://github.com/firebase/firebase-js-sdk) from 8.6.2 to 8.9.1.
- [Release notes](https://github.com/firebase/firebase-js-sdk/releases)
- [Changelog](https://github.com/firebase/firebase-js-sdk/blob/master/CHANGELOG.md)
- [Commits](https://github.com/firebase/firebase-js-sdk/compare/firebase@8.6.2...firebase@8.9.1)

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

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

Author: dependabot[bot]

package.json

@@ -14,7 +14,7 @@
   "dependencies": {
     "@material-ui/core": "^4.12.3",
     "@react-firebase/database": "^0.3.11",
-    "firebase": "^8.6.2",
+    "firebase": "^8.9.1",
     "react": "^17.0.2",
     "react-dom": "^17.0.2",
     "styled-components": "^5.3.0"