Fix postman collection and environment

doc/testing/postman/CAPIF.postman_collection.json

@@ -806,7 +806,7 @@
 				],
 				"body": {
 					"mode": "raw",
-					"raw": "{\n\"name\": {{USERNAME_INVOKER}}\n}",
+					"raw": "{\n\"name\": \"{{USERNAME_INVOKER}}\"\n}",
 					"options": {
 						"raw": {
 							"language": "json"

doc/testing/postman/CAPIF.postman_environment.json

@@ -32,6 +32,12 @@
 			"type": "default",
 			"enabled": true
 		},
+		{
+			"key": "USERNAME_INVOKER",
+			"value": "InvokerONE",
+			"type": "default",
+			"enabled": true
+		},
 		{
 			"key": "PASSWORD",
 			"value": "pass",