fix: Send signature and message in publishService body

The auth middleware expects username, signature, and message in the request
body for POST requests. The service object already contains signature and
message from rondevu.ts, so we just need to ensure they're sent by spreading
the service object and adding username.

src/api.ts

@@ -398,14 +398,15 @@ export class RondevuAPI {
      * Service FQN must include username: service:version@username
      */
     async publishService(service: ServiceRequest): Promise<Service> {
-        const auth = await this.generateAuthParams('publishService', service.serviceFqn);
-
         const response = await fetch(`${this.baseUrl}/services`, {
             method: 'POST',
             headers: {
                 'Content-Type': 'application/json',
             },
-            body: JSON.stringify({ ...service, username: auth.username }),
+            body: JSON.stringify({
+                ...service,
+                username: this.username
+            }),
         })
 
         if (!response.ok) {