Administration: Avoid PHP type error with `gmdate()` in `wp_dashboard… #24218

Job	Run time
Core running from build / MacOS	3m 26s
Core running from src / Linux	2m 36s
Core running from build / Linux	2m 43s
Core running from src / MacOS	4m 16s
Core running from build / Windows	5m 16s
Core running from src / Windows	6m 7s
Slack Notifications / Prepare notifications	3s
Slack Notifications / Success notifications	3s
Slack Notifications / Cancelled notifications	0s
Slack Notifications / Fixed notifications	0s
Slack Notifications / Failure notifications	0s
Failed workflow tasks	0s
	24m 30s

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