Update sonic-swss submodule (#11310)

Update sonic-swss submodule

```
639d10e [PFC_WD] [202012] Avoid applying ZeroBuffer Profiles to ingress PG when a PFC storm is detected (#2310)
475ae19 [202012] [cherry-pick] Apply `DSCP_TO_TC_MAP` from `PORT_QOS_MAP|global` to switch level (#2328)
aa6f855 [ci] Change artifact reference pipeline to common lib pipeline. (#2294)
752f8c5 [ci] Use correct branch when downloading artifact. (#2292)
b3fcc5d [ci] Improve azp trigger settings to automaticlly support new release branch. (#2289)
```