chore(deps-dev): bump docusaurus in /microsite (#2979)

Bumps [docusaurus](https://github.com/facebook/docusaurus) from 2.0.0-alpha.65 to 2.0.0-alpha.66.
- [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/compare/v2.0.0-alpha.65...v2.0.0-alpha.66)

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": "^8.0.0",
-    "docusaurus": "^2.0.0-alpha.65",
+    "docusaurus": "^2.0.0-alpha.66",
     "js-yaml": "^3.14.0",
     "prettier": "^2.0.5"
   },

microsite/yarn.lock

@@ -2233,10 +2233,10 @@ dir-glob@2.0.0:
     arrify "^1.0.1"
     path-type "^3.0.0"
 
-docusaurus@^2.0.0-alpha.65:
-  version "2.0.0-alpha.65"
-  resolved "https://registry.yarnpkg.com/docusaurus/-/docusaurus-2.0.0-alpha.65.tgz#e2b84985529deb79797aff52aa39ffbe03cd8a20"
-  integrity sha512-OEnKbXLPy3EpbQA/Dj0kakB6fg/Qni1LORTIero+5Q5G0QT5OH4FAbBQOy3L1qQH0S5Bv18zESxX9Nvclg20ag==
+docusaurus@^2.0.0-alpha.66:
+  version "2.0.0-alpha.66"
+  resolved "https://registry.yarnpkg.com/docusaurus/-/docusaurus-2.0.0-alpha.66.tgz#4dece48b838f773c4c973d9fe2546dd0bf2637cf"
+  integrity sha512-/HmRt3hEqpvZRdR2JRYKpwNUgalO14exxuwQu2vXW5eYzcKbQ922+3SxG7mF+LE8f7KOmgY+A3eS3SEyq+S3XA==
   dependencies:
     "@babel/core" "^7.9.0"
     "@babel/plugin-proposal-class-properties" "^7.8.3"