fix(data-events): metadata accepts non-string values in Unstable base spec (#592)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: pkubicki

descriptions/0/api.intercom.io.yaml

@@ -30736,8 +30736,7 @@ components:
         metadata:
           type: object
           description: Optional metadata about the event.
-          additionalProperties:
-            type: string
+          additionalProperties: true
           example:
             invite_code: ADDAFRIEND
       anyOf:
@@ -33036,8 +33035,7 @@ components:
         metadata:
           type: object
           description: Optional metadata about the event.
-          additionalProperties:
-            type: string
+          additionalProperties: true
           example:
             invite_code: ADDAFRIEND
       required: