[swss] Update Submodule

Including the below commits to update swss submodule
8448a60 [vs tests]Migrating sonic-swss tests to use hwsku instead of fakeplatform (sonic-net#1978)
faa26db Fix random failure in PR/CI build. (sonic-net#2006)
e03edb6 Allow interface type value none (sonic-net#1991)
71b9650 [orchagent] Fix group name of port-buffer-drop in flexcounterorch.cpp (sonic-net#1967)
facdef5 [VS test] Skip flaky virtual chassis test (sonic-net#2004)
8261c1f [pytest]: Increase timeout when checking services (sonic-net#2000)
67278be [teammgrd]: Handle LAGs cleanup gracefully on Warm/Fast reboot. (sonic-net#1934)
e92c1df Enable FEC statistics collection for Ethernet ports (sonic-net#1994)
9f30ca1 VxLAN Tunnel Counters and Rates implementation (sonic-net#1859)

Signed-off-by: Sudharsan Dhamal Gopalarathnam <sudharsand@nvidia.com>