Importing github commit signing keys via powershell

ImportGithubSigningKeys.ps1

<#
.SYNOPSIS
    Imports github pgp signing keys for one or more users.
.DESCRIPTION
    Imports github commit signing keys for one or more github usernames into your gpg key ring.
    You still need to assign trust levels to keys after their import, see https://www.gnupg.org/gph/en/manual/x334.html
.PARAMETER Users
    A comma seperated list of github usernames whose keys will be retrieved amd imported.
.EXAMPLE
    .\ImportGithubSigningKeys blowdart 
.LINK
    https://help.github.com/articles/signing-commits-using-gpg/
    https://www.gnupg.org/gph/en/manual/x334.html
   
#>
[CmdletBinding(DefaultParameterSetName="Users")]
param(
    [Parameter(Mandatory=$true, Position=0, ParameterSetName="Users", 
               ValueFromPipeline=$true, 
               ValueFromPipelineByPropertyName=$true,
               HelpMessage="Users whose keys to import...")]
    [ValidateNotNullOrEmpty()]
    [string[]]
    $githubUsers
)
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$importFileName = "importedGitHubKeys.asc"
$githubUsers |% {Invoke-WebRequest https://api.github.com/users/$_/gpg_keys | ConvertFrom-Json } |% {$_.raw_key} | Out-File -Append -Encoding ascii $importFileName
gpg --import $importFileName
Remove-Item $importFilename