像这样修改部分代码:

$query = "Select
    [System.Id],
    [System.WorkItemType],
    [System.Title],
    [System.AssignedTo],
    [System.State]
From WorkItemLinks
WHERE (
        Source.[System.TeamProject] = '$projectName'
        AND Source.[System.State] <> 'Removed'
    ) AND (
        Source.[System.WorkItemType] = 'Epic')
        AND ([System.Links.LinkType] = 'System.LinkTypes.Hierarchy-Forward'
    ) AND (Target.[System.WorkItemType] = 'UserStory') mode (Recursive)
"

$body = @{query=$query} | ConvertTo-Json
$result = Invoke-RestMethod -Uri $uri -Method Post -ContentType "application/json" -Headers @{Authorization=("Basic $base64AuthInfo")} -Body $body