chore(deps-dev): update rollup from ^1.20.1 to ^1.20.2 (#426)

Updates the requirements on [rollup](https://github.com/rollup/rollup) to permit the latest version.
- [Release notes](https://github.com/rollup/rollup/releases)
- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
- [Commits](rollup/rollup@v1.20.1...v1.20.2)

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

Co-authored-by: null <27856297+dependabot-preview[bot]@users.noreply.github.com>

package.json

@@ -61,7 +61,7 @@
     "markdownlint-cli": "^0.18.0",
     "npm-run-all": "^4.1.5",
     "prettier": "^1.18.2",
-    "rollup": "^1.20.1",
+    "rollup": "^1.20.2",
     "rollup-plugin-babel": "^4.3.3",
     "rollup-plugin-terser": "^5.1.1"
   },