Update schema/workflow.yaml

Co-authored-by: Charles d'Avernas <charles.davernas@neuroglia.io>
Signed-off-by: Francisco Javier Tirado Sarti <ftirados@redhat.com>

Author: fjtirado

schema/workflow.yaml

@@ -1294,9 +1294,9 @@ $defs:
             description: An expression based event data schema.
       data:
         title: EventData
-        description: Allow filtering by data content
+        description: The event's payload data
         oneOf:
-          - type: string
+          - $ref: '#/$defs/runtimeExpression'
           - type: object 
     additionalProperties: true
   eventConsumptionStrategy: