Billing_plan field deprecation - correction start date (#3244)

Co-authored-by: ci.datadog-api-spec <packages@datadoghq.com>

Author: api-clients-generation-pipeline[bot]

.generator/schemas/v1/openapi.yaml

@@ -20236,7 +20236,7 @@ components:
           type: string
         billing_plan:
           deprecated: true
-          description: The billing plan (metadata). (Deprecated from May 2026)
+          description: The billing plan (metadata). (Deprecated from June 2026)
           type: string
         end_date:
           description: Shows the last date of usage.

src/datadog_api_client/v1/model/usage_billable_summary_hour.py

@@ -75,7 +75,7 @@ def __init__(
         :param account_public_id: The account public ID.
         :type account_public_id: str, optional
 
-        :param billing_plan: The billing plan (metadata). (Deprecated from May 2026) **Deprecated**.
+        :param billing_plan: The billing plan (metadata). (Deprecated from June 2026) **Deprecated**.
         :type billing_plan: str, optional
 
         :param end_date: Shows the last date of usage.