Add repository.url to fix npm provenance issue (#1369)

> an error occurred while publishing @livekit/protocol: E422
422 Unprocessable Entity - PUT
https://registry.npmjs.org/@livekit%2fprotocol - Error verifying
sigstore provenance bundle: Failed to validate repository information:
package.json: "repository.url" is "", expected to match
"https://github.com/livekit/protocol" from provenance

Author: 1egoman

package.json

@@ -18,5 +18,8 @@
       "js-yaml": "3.14.2"
     }
   },
+  "repository": {
+    "url": "https://github.com/livekit/protocol"
+  },
   "packageManager": "[email protected]"
 }