[Fixed in 1.5.2] 404 error on authorize

```
Client error: `GET https://api.backblazeb2.com/b2api/v1//b2_authorize_account` resulted in a `404 Not Found` response:
{
  \"code\": \"not_found\",
  \"message\": \"/b2api/v1//b2_authorize_account\",
  \"status\": 404
}
```

This seems to have only occurred recently. Removing the extra forward slash after `v1` seems to fix the issue.