Update sonic-swss-common submodule (sonic-net#11470)

#### Why I did it

Submodule update for sonic-swss-common with following change:

597b022 Add SonicDBConfig.getInstanceList() API (sonic-net#639)
7073dc6 add table name for vlan_stacking (sonic-net#646)
7e39f31 Add SonicV2Connector::set method for int value. (sonic-net#648)
154cc9c Improve hset and hdel performance with RedisPipeline. (sonic-net#647) 


#### How I did it

#### How to verify it

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

<!--
- Note we only backport fixes to a release branch, *not* features!
- Please also provide a reason for the backporting below.
- e.g.
- [x] 202006
-->

- [ ] 201811
- [ ] 201911
- [ ] 202006
- [ ] 202012
- [ ] 202106

#### Description for the changelog
Submodule update for sonic-swss-common with following change:

597b022 Add SonicDBConfig.getInstanceList() API (sonic-net#639)
7073dc6 add table name for vlan_stacking (sonic-net#646)
7e39f31 Add SonicV2Connector::set method for int value. (sonic-net#648)
154cc9c Improve hset and hdel performance with RedisPipeline. (sonic-net#647) 


#### A picture of a cute animal (not mandatory but encouraged)