upgrade livereload plugin (sveltejs#167)

Author: antony

package.json

@@ -10,7 +10,7 @@
     "@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-livereload": "^2.0.0",
     "rollup-plugin-svelte": "^6.0.0",
     "rollup-plugin-terser": "^7.0.0",
     "svelte": "^3.0.0"