change the event type of tags from string to object (#26579)

* change the event type of tags from string to object

* ran prettier check

Author: Supriya-R-Dixit

specification/eventgrid/data-plane/Microsoft.ResourceNotifications/stable/2018-01-01/common.json

@@ -29,7 +29,10 @@
         },
         "tags": {
           "description": "the tags on the resource for which the event is being emitted",
-          "type": "string"
+          "type": "object",
+          "additionalProperties": {
+            "type": "string"
+          }
         },
         "properties": {
           "description": "properties in the payload of the resource for which the event is being emitted",