Upgrade rollup-plugin-terser to 7.0 (#164)

Author: benmccann

package.json

@@ -12,7 +12,7 @@
     "rollup": "^2.3.4",
     "rollup-plugin-livereload": "^1.0.0",
     "rollup-plugin-svelte": "^5.0.3",
-    "rollup-plugin-terser": "^6.0.0",
+    "rollup-plugin-terser": "^7.0.0",
     "svelte": "^3.0.0"
   },
   "dependencies": {