[sonic-utilities] Update submodule. (#7227)

3f2a296 - 2021-04-06 | [fast-reboot] Fix fast-reboot-dump.py SonicV2Connector after late merge (# 1546) [Shlomi Bitton]
87b2481 - 2021-04-04 | Reduce time taken by show commands on multi-asic platforms (# 1544) [Abhishek Dosi]
9bbc25f - 2021-04-04 | [config] Eliminate race condition between reloading Monit config and monitoring container_checker (# 1543) [Yong Zhao]
e0f678a - 2021-04-03 | [setup.py]: move the module to test requirement (# 1542) [Guohan Lu]
37376dd - 2021-04-02 | [ci]: download latest docker-sonic-vs from sonic-swss repo (# 1541) [Guohan Lu]
d55d406 - 2021-3-31 | [acl_loader]: add iptype match to the rules for dataplane acl (# 1540) [Guohan Lu]
12fc01e - 2021-04-03 | [reboot] No need enable the Linux magic system request key (# 1538) [Yong Zhao]
0ce6a25 - 2021-04-05 | [show][config] cli support for firmware upgrade on Y-Cable (# 1528) [Vaibhav Dahiya]
e9cfb32 - 2021-04-02 | [fast-reboot] Fix dump script to support PortChannels in a VLAN group (# 1393) [Shlomi Bitton]

Signed-off-by: Yong Zhao <yozhao@microsoft.com>