fix webhook alerts

Author: JohnDuprey

Modules/CIPPCore/Public/Entrypoints/Activity Triggers/Push-SchedulerCIPPNotifications.ps1

@@ -106,7 +106,7 @@ function Push-SchedulerCIPPNotifications {
     try {
         Write-Information $($config | ConvertTo-Json)
         Write-Information $config.webhook
-        if ($Config.webhook -ne '' -and $null) {
+        if (![string]::IsNullOrEmpty($config.webhook)) {
             if ($Currentlog) {
                 $JSONContent = $Currentlog | ConvertTo-Json -Compress
                 Send-CIPPAlert -Type 'webhook' -JSONContent $JSONContent -TenantFilter $Tenant -APIName 'Alerts'