For me this works fine:

{
  "isBackground": true,
  "type": "shell",
  "label": "terminal",
  "command": "/bin/zsh",
  "args": ["-l"],
  "problemMatcher": [],
  "presentation": {
    "echo": false,
    "focus": true,
    "panel": "dedicated"
  },
  "runOptions": {
    "runOn": "folderOpen"
  }
}