Corrected ESU timestamp

Author: Alexander (Sasha) Nosov

samples/manage/azure-arc-enabled-sql-server/modify-license-type/modify-license-type.ps1

@@ -210,7 +210,7 @@ foreach ($sub in $subscriptions){
         if ($EnableESU) {
             if (($settings["LicenseType"] | select-string "Paid","PAYG") -or  ($EnableESU -eq "No")) {
                 $settings["enableExtendedSecurityUpdates"] = ($EnableESU -eq "Yes")
-                $settings["esuLastUpdatedTimestamp"] = [DateTime]::UtcNow.ToString((Get-Culture).DateTimeFormat.UniversalSortableDateTimePattern)
+                $settings["esuLastUpdatedTimestamp"] = [DateTime]::UtcNow.ToString('yyyy-MM-ddTHH:mm:ss.fffZ')
                 $WriteSettings = $true
             } else {
                 write-host "The configured license type does not support ESUs"