Upgrade Rollup plugins (#156)

Author: benmccann

package.json

@@ -7,12 +7,12 @@
     "start": "sirv public"
   },
   "devDependencies": {
-    "@rollup/plugin-commonjs": "^12.0.0",
+    "@rollup/plugin-commonjs": "^14.0.0",
     "@rollup/plugin-node-resolve": "^8.0.0",
     "rollup": "^2.3.4",
     "rollup-plugin-livereload": "^1.0.0",
     "rollup-plugin-svelte": "^5.0.3",
-    "rollup-plugin-terser": "^5.1.2",
+    "rollup-plugin-terser": "^6.0.0",
     "svelte": "^3.0.0"
   },
   "dependencies": {