Warn if using an unsupported Node version

lib/helpers.js

@@ -1,6 +1,10 @@
 import { ACCOUNT_EMAIL, ACCOUNT_ID, API_HOST, API_TOKEN } from "./constants.js";
 
 if (!globalThis.fetch) {
+  console.warn("\nIMPORTANT: Your Node.js version doesn't have native fetch support and may not be supported in the future. Please update to v18 or later.\n")
+  // Advise what to do if running in GitHub Actions
+  if (process.env.GITHUB_WORKSPACE) console.warn("Since you're running in GitHub Actions, you should update your Actions workflow configuration to use Node v18 or higher.") 
+  // Import node-fetch since there's no native fetch in this environment
   globalThis.fetch = (await import("node-fetch")).default;
 }