[submodule]: Advance swss submodule pointer (#8288)

This PR includes the following commits

a67d8af [202012][portsorch] fix errors when moving port from one lag to another (sonic-net/sonic-swss#1819)
04105a4 [debugcounterorch] check if counter type is supported before querying (sonic-net/sonic-swss#1789)
ac7f5cff Td2: Reclaim buffer from unused ports (sonic-net/sonic-swss#1830)
f54b7d0 [Dynamic Buffer Calc][202012]Bug fix: Don't create lossless buffer profile for active ports without speed configured  (sonic-net/sonic-swss#1820)

Signed-off-by: Neetha John <[email protected]>