Bump @rollup/plugin-commonjs from 19.0.2 to 21.0.1

Bumps [@rollup/plugin-commonjs](https://github.com/rollup/plugins/tree/HEAD/packages/commonjs) from 19.0.2 to 21.0.1.
- [Release notes](https://github.com/rollup/plugins/releases)
- [Changelog](https://github.com/rollup/plugins/blob/master/packages/commonjs/CHANGELOG.md)
- [Commits](https://github.com/rollup/plugins/commits/commonjs-v21.0.1/packages/commonjs)

---
updated-dependencies:
- dependency-name: "@rollup/plugin-commonjs"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

package.json

@@ -52,7 +52,7 @@
     "@babel/core": "^7.4.5",
     "@babel/preset-env": "^7.4.5",
     "@rollup/plugin-babel": "^5.3.0",
-    "@rollup/plugin-commonjs": "^19.0.0",
+    "@rollup/plugin-commonjs": "^21.0.1",
     "@rollup/plugin-node-resolve": "^13.0.0",
     "autoprefixer": "^10.2.4",
     "cssnano": "^5.0.4",