use more recent version of Rollup for treeshakability test (#3574)

Author: Conduitry

package-lock.json

@@ -61,7 +61,7 @@
     "@typescript-eslint/eslint-plugin": "^1.13.0",
     "@typescript-eslint/parser": "^2.1.0",
     "acorn": "^7.0.0",
-    "agadoo": "^1.0.1",
+    "agadoo": "^1.1.0",
     "c8": "^5.0.1",
     "codecov": "^3.5.0",
     "css-tree": "1.0.0-alpha22",
@@ -76,7 +76,7 @@
     "magic-string": "^0.25.3",
     "mocha": "^6.2.0",
     "puppeteer": "^1.19.0",
-    "rollup": "^1.20.3",
+    "rollup": "^1.21.4",
     "rollup-plugin-commonjs": "^10.1.0",
     "rollup-plugin-json": "^4.0.0",
     "rollup-plugin-node-resolve": "^5.2.0",