chore(deps-dev): update rollup requirement from ^1.14.6 to ^1.15.1

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@v1.14.6...v1.15.1)

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

package.json

@@ -51,7 +51,7 @@
     "prettier": "^1.18.2",
     "prettier-package-json": "^2.1.0",
     "rimraf": "^2.6.3",
-    "rollup": "^1.14.6"
+    "rollup": "^1.15.1"
   },
   "publishConfig": {
     "registry": "https://registry.npmjs.org/"