chore(package): update rollup-plugin-terser to version 6.0.1

Closes #72

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "rollup-plugin-node-resolve": "^5.2.0",
     "rollup-plugin-replace": "^2.2.0",
     "rollup-plugin-size-snapshot": "^0.10.0",
-    "rollup-plugin-terser": "^5.1.2",
+    "rollup-plugin-terser": "^6.0.1",
     "sass-loader": "^8.0.0",
     "style-loader": "^1.0.0",
     "ts-jest": "^24.0.0",