[submodule]: sonic-utilities (sonic-net#5606)

* b6af9f4 2020-10-12 | Fix expected neighbor when multiple ports connect to same neighbor (sonic-net#1162) [lguohan]
* a71c72b 2020-10-12 | [show] Add 'show' CLI for system-health feature (sonic-net#971) [shlomibitton]
* 561d133 2020-10-10 | [README.md] Add instructions for setting up a build/test environment (sonic-net#1161) [Joe LeVeque]

Signed-off-by: Guohan Lu <lguohan@gmail.com>