Bump prop-types from 15.7.2 to 15.8.1 (#276)

Bumps [prop-types](https://github.com/facebook/prop-types) from 15.7.2 to 15.8.1.
- [Release notes](https://github.com/facebook/prop-types/releases)
- [Changelog](https://github.com/facebook/prop-types/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/prop-types/compare/v15.7.2...v15.8.1)

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

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

package.json

@@ -29,7 +29,7 @@
     "matrix-js-sdk": "^15.4.0",
     "micromark": "^3.0.3",
     "micromark-extension-gfm": "^1.0.0",
-    "prop-types": "^15.7.2",
+    "prop-types": "^15.8.1",
     "react": "^17.0.2",
     "react-autosize-textarea": "^7.1.0",
     "react-dom": "^17.0.2",