TLS Certificate test in powershell core

TLSCert.ps1

function Test-WebServerCertificate {
    [CmdletBinding()]
        param(
            [Parameter(Mandatory = $true, ValueFromPipeline = $true, Position = 0)]
            [string]$URL,
            [Parameter(Position = 1)]
            [ValidateRange(1,65535)]
            [int]$Port = 443,
            [Parameter(Position = 2)]
            [Net.WebProxy]$Proxy,
            [Parameter(Position = 3)]
            [int]$Timeout = 15000,
            [switch]$UseUserContext
        )
        
        Process {
            $ConnectString = "https://$url`:$port"
            $WebRequest = [Net.WebRequest]::Create($ConnectString)
            $WebRequest.Proxy = $Proxy
            $WebRequest.Credentials = $null
            $WebRequest.Timeout = $Timeout
            $WebRequest.AllowAutoRedirect = $true
            $cert = [PSCustomObject]@{
                URI = $ConnectString
                Issuer = $null
                Subject = $null
                NotBefore = $null
                NotAfter = $null
            }
            $WebRequest.ServerCertificateValidationCallback = {
                $cert.Issuer = $args[1].Issuer 
                $cert.Subject = $args[1].Subject 
                $cert.NotBefore = $args[1].NotBefore 
                $cert.NotAfter = $args[1].NotAfter 
                $true
            }
            try {$Response = $WebRequest.GetResponse()}
            catch {}
    
            $cert    
        }
    }

$sites = @(
    "www.facebook.com"
    )

$sites | Test-WebServerCertificate | where { $_.NotAfter -lt ([DateTime]::Now.AddMonths(10)) } | select URI, NotAfter