build(deps): Bump react-rails from 2.6.1 to 3.2.1

Bumps [react-rails](https://github.com/reactjs/react-rails) from 2.6.1 to 3.2.1.
- [Release notes](https://github.com/reactjs/react-rails/releases)
- [Changelog](https://github.com/reactjs/react-rails/blob/master/CHANGELOG.md)
- [Commits](reactjs/react-rails@v2.6.1...v3.2.1)

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

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

Gemfile.lock

@@ -100,7 +100,7 @@ GEM
     diff-lcs (1.5.1)
     drb (2.2.1)
     erubi (1.12.0)
-    execjs (2.8.1)
+    execjs (2.9.1)
     factory_bot (6.4.6)
       activesupport (>= 5.0.0)
     factory_bot_rails (6.4.3)
@@ -219,7 +219,7 @@ GEM
       ffi (~> 1.0)
     rdoc (6.7.0)
       psych (>= 4.0.0)
-    react-rails (2.6.1)
+    react-rails (3.2.1)
       babel-transpiler (>= 0.7.0)
       connection_pool
       execjs