Update workflow.yaml

Author: cdavernas

schema/workflow.yaml

@@ -1,4 +1,4 @@
-$id: https://serverlessworkflow.io/schemas/1.0.0/workflow.yaml
+$id: https://serverlessworkflow.io/schemas/1.0.0-alpha3/workflow.yaml
 $schema: https://json-schema.org/draft/2020-12/schema
 description: Serverless Workflow DSL - Workflow Schema.
 type: object
@@ -1486,4 +1486,4 @@ $defs:
     type: string
     title: RuntimeExpression
     description: A runtime expression.
-    pattern: "^\\s*\\$\\{.+\\}\\s*$"
+    pattern: "^\\s*\\$\\{.+\\}\\s*$"