Bump @babel/plugin-proposal-class-properties from 7.7.4 to 7.8.3 (#12891)

Bumps [@babel/plugin-proposal-class-properties](https://github.com/babel/babel) from 7.7.4 to 7.8.3.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.4...v7.8.3)

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

package.json

@@ -60,7 +60,7 @@
   "private": true,
   "dependencies": {
     "@babel/core": "^7.7.7",
-    "@babel/plugin-proposal-class-properties": "^7.7.4",
+    "@babel/plugin-proposal-class-properties": "^7.8.3",
     "@babel/plugin-proposal-decorators": "^7.8.0",
     "@babel/plugin-transform-react-inline-elements": "^7.8.0",
     "@babel/plugin-transform-runtime": "^7.7.6",