Bump rollup from 2.7.3 to 2.7.6 (#30728)

Bumps [rollup](https://github.com/rollup/rollup) from 2.7.3 to 2.7.6.
- [Release notes](https://github.com/rollup/rollup/releases)
- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rollup/rollup/compare/v2.7.3...v2.7.6)

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

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

package.json

@@ -126,7 +126,7 @@
     "npm-run-all": "^4.1.5",
     "popper.js": "^1.16.0",
     "postcss-cli": "^7.1.1",
-    "rollup": "^2.7.3",
+    "rollup": "^2.7.6",
     "rollup-plugin-babel": "^4.4.0",
     "rollup-plugin-istanbul": "^2.0.1",
     "serve": "^11.3.0",