Bump rollup from 2.60.2 to 2.68.0

Bumps [rollup](https://github.com/rollup/rollup) from 2.60.2 to 2.68.0.
- [Release notes](https://github.com/rollup/rollup/releases)
- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
- [Commits](rollup/rollup@v2.60.2...v2.68.0)

---
updated-dependencies:
- dependency-name: rollup
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

package.json

@@ -73,7 +73,7 @@
     "postcss": "^8.4.4",
     "postcss-cli": "^9.1.0",
     "postcss-understrap-palette-generator": "git+https://github.com/understrap/postcss-understrap-palette-generator.git",
-    "rollup": "^2.60.2",
+    "rollup": "^2.68.0",
     "sass": "^1.44.0",
     "terser": "^5.10.0"
   }