Bump react-markdown from 7.1.2 to 8.0.3 in /client

Bumps [react-markdown](https://github.com/remarkjs/react-markdown) from 7.1.2 to 8.0.3.
- [Release notes](https://github.com/remarkjs/react-markdown/releases)
- [Changelog](https://github.com/remarkjs/react-markdown/blob/main/changelog.md)
- [Commits](remarkjs/react-markdown@7.1.2...8.0.3)

---
updated-dependencies:
- dependency-name: react-markdown
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

client/package-lock.json

@@ -17,7 +17,7 @@
     "react-app-rewired": "^2.2.1",
     "react-dimensions": "^1.3.1",
     "react-dom": "^17.0.2",
-    "react-markdown": "^7.1.1",
+    "react-markdown": "^8.0.3",
     "react-router": "^5.2.1",
     "react-router-dom": "^5.3.0",
     "react-scripts": "^4.0.3",