MacOS 11.4 is detected as MacOS 11.0

Hi,
i am using ngx-device-detector in angular 11/electron 11 environment. I am currently on the latest macOS 11.4 version

stringified Output of getDeviceInfo():
```
{
"userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 11_4_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Electron/11.4.7 Safari/537.36",
"os": "Mac",
"browser": "Chrome",
"device": "Macintosh",
"os_version": "mac-os-x-11-0",
"browser_version": "87.0.4280.141",
"deviceType": "desktop",
"orientation": "landscape"
}
```
Although the user-agent outputs the right version 11.4, the os_version is shown as mac-os-x-11-0.
The expected output were either mac-os-11-4 or mac-os-11.