build(deps-dev): bump docusaurus in /microsite (#3543)

Bumps [docusaurus](https://github.com/facebook/docusaurus) from 2.0.0-alpha.66 to 2.0.0-alpha.378053ac5.
- [Release notes](https://github.com/facebook/docusaurus/releases)
- [Changelog](https://github.com/facebook/docusaurus/blob/master/CHANGELOG-2.x.md)
- [Commits](https://github.com/facebook/docusaurus/commits)

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

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

microsite/package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "@spotify/prettier-config": "^9.0.0",
-    "docusaurus": "^2.0.0-alpha.66",
+    "docusaurus": "^2.0.0-alpha.378053ac5",
     "js-yaml": "^3.14.0",
     "prettier": "^2.2.1"
   },