fix(Mailjet Trigger Node): Fix issue that node could not get activated (#3281)

* 🔨 fix and clean up

* ⚡ Improvements

Co-authored-by: ricardo <ricardoespinoza105@gmail.com>

packages/nodes-base/credentials/MailjetSmsApi.credentials.ts

@@ -1,4 +1,6 @@
 import {
+	IAuthenticateHeaderAuth,
+	ICredentialTestRequest,
 	ICredentialType,
 	INodeProperties,
 } from 'n8n-workflow';
@@ -15,4 +17,18 @@ export class MailjetSmsApi implements ICredentialType {
 			default: '',
 		},
 	];
+	authenticate: IAuthenticateHeaderAuth = {
+		type: 'headerAuth',
+		properties: {
+			name: 'Authorization',
+			value: '=Bearer {{$credentials.token}}',
+		},
+	};
+	test: ICredentialTestRequest = {
+		request: {
+			baseURL: `https://api.mailjet.com`,
+			url: '/v4/sms',
+			method: 'GET',
+		},
+	};
 }