Update sonic-swss-common submodule (sonic-net#10872)

Updating sonic-utilities sub module with the following commits

    84dbd93 Clear the fvs vector before popping the message out of notification
    a90b2b7 selectabletimer: add mutex to start() and stop()
    7ae22be Fix SIGTERM can't terminate PubSub::listen issue

#### Why I did it

    To fix hostcfgd can't terminate by sigint issue, need update sonic-swss-common submodule.  

#### How I did it

#### How to verify it

#### Which release branch to backport (provide reason below if selected)

#### Description for the changelog

    84dbd93 Clear the fvs vector before popping the message out of notification
    a90b2b7 selectabletimer: add mutex to start() and stop()
    7ae22be Fix SIGTERM can't terminate PubSub::listen issue

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