chore(deps-dev): bump rollup from 2.19.0 to 2.21.0

Bumps [rollup](https://github.com/rollup/rollup) from 2.19.0 to 2.21.0.
- [Release notes](https://github.com/rollup/rollup/releases)
- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
- [Commits](rollup/rollup@v2.19.0...v2.21.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -64,7 +64,7 @@
     "eslint-plugin-vue": "^6.2.2",
     "husky": "^4.2.5",
     "prettier": "^2.0.5",
-    "rollup": "^2.19.0",
+    "rollup": "^2.21.0",
     "rollup-plugin-babel": "^4.4.0",
     "rollup-plugin-terser": "^6.1.0",
     "rollup-plugin-vue": "^5.1.9",