Update dependency rollup to v2.6.1 (#66)

Author: renovate-bot

package.json

@@ -46,7 +46,7 @@
     "npm-run-all": "4.1.5",
     "prettier": "2.0.4",
     "rimraf": "3.0.2",
-    "rollup": "2.2.0",
+    "rollup": "2.6.1",
     "shx": "0.3.2",
     "tslib": "1.11.1",
     "typescript": "3.8.3"