[submodule][202012] Update submodule sonic-utilities to the latest HE…

…AD (#15532)

#### Why I did it
Update submodule sonic-utilities to the latest HEAD
```
50296b90 - [202012][dhcp-relay] Fix dhcp6relay counter issue (#2866) (#2873) (Fri Jun 30 18:08:53 2023 +0800) <Yaqiang Zhu>
160030c4 - [202012][dhcp_relay] Add "Reconfigure", "Information-Request", "Malformed" counter options (#2844) (Sun Jun 11 20:35:30 2023 -0700) <kellyyeh>
e6289ced - [vlan][dhcp_relay] Clear dhcpv6 relay counter while deleting vlan (#2852) (Fri Jun 2 18:20:21 2023 +0000) <Yaqiang Zhu>
885082ec - correctly parsing complete ipv6 vnet info (#2827) (Thu May 25 06:01:40 2023 +0000) <Keith Lu>
```

##### Work item tracking
- Microsoft ADO 22635770