feat(github-workflow): add timezone property to on.schedule[] items (SchemaStore#5479)

See
- GitHub blog
  https://github.blog/changelog/2026-03-19-github-actions-late-march-2026-updates/#github-actions-timezone-support-for-scheduled-workflows
- `on.schedule` docs
  https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#onschedule
- github/docs@1ead651 (Update schedule docs to include timezone (pr 60290), 2026-03-19)
- actions/languageservices@a7f581b (Add timezone to workflow and pass FF (pr 334), 2026-03-06)

Author: muzimuzhi

src/schemas/json/github-workflow.json

@@ -1779,16 +1779,22 @@
               "description": "You can use the GitHub API to trigger a webhook event called repository_dispatch when you want to trigger a workflow for activity that happens outside of GitHub. For more information, see https://developer.github.com/v3/repos/#create-a-repository-dispatch-event.\nTo trigger the custom repository_dispatch webhook event, you must send a POST request to a GitHub API endpoint and provide an event_type name to describe the activity type. To trigger a workflow run, you must also configure your workflow to use the repository_dispatch event."
             },
             "schedule": {
-              "$comment": "https://help.github.com/en/github/automating-your-workflow-with-github-actions/events-that-trigger-workflows#scheduled-events-schedule",
-              "description": "You can schedule a workflow to run at specific UTC times using POSIX cron syntax (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/crontab.html#tag_20_25_07). Scheduled workflows run on the latest commit on the default or base branch. The shortest interval you can run scheduled workflows is once every 5 minutes.\nNote: GitHub Actions does not support the non-standard syntax @yearly, @monthly, @weekly, @daily, @hourly, and @reboot.\nYou can use crontab guru (https://crontab.guru/). to help generate your cron syntax and confirm what time it will run. To help you get started, there is also a list of crontab guru examples (https://crontab.guru/examples.html).",
+              "$comment": "https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#schedule",
+              "description": "You can schedule a workflow to run at specific UTC times using POSIX cron syntax (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/crontab.html#tag_20_25_07). You can optionally specify a timezone using an IANA timezone string (https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) for timezone-aware scheduling. Scheduled workflows run on the latest commit on the default or base branch. The shortest interval you can run scheduled workflows is once every 5 minutes.\nNote: GitHub Actions does not support the non-standard syntax @yearly, @monthly, @weekly, @daily, @hourly, and @reboot.\nYou can use crontab guru (https://crontab.guru/) to help generate your cron syntax and confirm what time it will run. To help you get started, there is also a list of crontab guru examples (https://crontab.guru/examples.html).",
               "type": "array",
               "items": {
                 "type": "object",
                 "properties": {
                   "cron": {
+                    "description": "A cron expression that represents a schedule. A scheduled workflow will run at most once every 5 minutes.",
+                    "type": "string"
+                  },
+                  "timezone": {
+                    "description": "A string that represents the time zone a scheduled workflow will run relative to in IANA format (e.g. 'America/New_York' or 'Europe/London'). If omitted, the workflow will run relative to midnight UTC.",
                     "type": "string"
                   }
                 },
+                "required": ["cron"],
                 "additionalProperties": false
               },
               "minItems": 1