Re-add sideEffects false to package.json

This appears to have been lost in the 4.0.0 release

Author: me4502

package.json

@@ -15,6 +15,7 @@
   "files": [
     "dist"
   ],
+  "sideEffects": false,
   "scripts": {
     "clear": "npm run clear:parcel-cache & npm run clear:builds & npm run clear:node_modules",
     "clear:builds": "rm -rf ./packages/*/dist",