add missing devdep @parcel/watcher

Author: legobeat

package-lock.json

@@ -304,6 +304,7 @@
     "browser-tests:test-rollup": "karma start --single-run --browsers ChromeHeadless test/karma.rollup.conf.js"
   },
   "devDependencies": {
+    "@parcel/watcher": "2.4.1",
     "@rollup/plugin-commonjs": "22.0.1",
     "@rollup/plugin-node-resolve": "13.3.0",
     "@types/estree": "1.0.0",