PATCH /v2/accounts/:id

Update an account's mutable attributes. `excludeFromReporting`,
`legalEntity`, and the `depository` / `depositories` relationships
are NOT mutable here.

Path params:
  id (required) — Account identifier.

Request:
{
  "data": {
    "type": "account",
    "id":   "string (must match path id)",
    "attributes": {
      "name":               "string (optional)",
      "externalIdentifier": "string (optional)",
      "ccyCode":            "string (optional) — ISO 4217"
    }
  }
}

Response (204 No Content):
  Empty body.