List all VPN instances

curl --request GET \
  --url https://api.altostrat.io/instances \
  --header 'Authorization: Bearer <token>'

[
  {
    "id": "<string>",
    "name": "<string>",
    "region": "<string>",
    "hostname": "<string>",
    "configured": true,
    "rsa_ready": true,
    "diffie_hellman_ready": true,
    "server_ready": true,
    "status": [
      "<any>"
    ],
    "pushed_routes": [
      "<string>"
    ],
    "public_dns": [
      "127.0.0.1"
    ],
    "split_dns": [
      "<string>"
    ],
    "domains": [
      "<string>"
    ],
    "dns_custom": [
      {
        "name": "<string>",
        "type": "A",
        "value": "<string>"
      }
    ],
    "firewall": [
      {}
    ],
    "created_at": "2023-11-07T05:31:56Z"
  }
]