[202012][submodule] Update sonic-utilities submodule

Update sonic-utilities submodule pointer to include the following:
* Fix test for pfcwd_sw_enable in db_migrator_test ([sonic-net#2252](sonic-net/sonic-utilities#2252))
* [DHCPv6] [202012] Update the dhcpv6_relay config/show cli ([sonic-net#2271](sonic-net/sonic-utilities#2271))
* [vnet_route_check] Align DB data parse logic with format used by swsscommon API ([sonic-net#2268](sonic-net/sonic-utilities#2268))
* [202012] [generate_dump] allow to extend dump with plugin scripts ([sonic-net#2269](sonic-net/sonic-utilities#2269))

Signed-off-by: dprital <[email protected]>