$Username = '!username!'
$Password = '!password!'
$BuildTypeId = '!build type id from teamcity!'

$Pair = "$($Username):$($Password)"
$EncodedCredentials = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes($Pair))
$Headers = @{
  Authorization = "Basic $EncodedCredentials";
  Accept = "application/json"
}

$Body = '<build branchName="v1.26.1"><buildType id="#{buildTypeId}"/><comment><text>Build was triggered by GitLab.</text></comment><properties /></build>' -Replace "#{buildTypeId}", $BuildTypeId
Invoke-WebRequest -Uri 'http://teamcity.host/httpAuth/app/rest/buildQueue' -Method POST -Body $Body -UseBasicParsing -Headers $Headers -ContentType "application/xml"