Bump rollup from 1.32.1 to 2.1.0

Bumps [rollup](https://github.com/rollup/rollup) from 1.32.1 to 2.1.0.
- [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/v1.32.1...v2.1.0)

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

package.json

@@ -88,7 +88,7 @@
     "pngjs": "^3.4.0",
     "proj4": "2.6.0",
     "puppeteer": "~2.1.0",
-    "rollup": "^1.25.1",
+    "rollup": "^2.1.0",
     "rollup-plugin-babel": "^4.3.3",
     "rollup-plugin-commonjs": "^10.0.0",
     "rollup-plugin-node-resolve": "^5.2.0",