Upgrade Go version to 1.16

[tisonkun]

Development Task

So far, Dumpling development uses Go 1.13 which is end of life for a while. Also for supporting running on Apple M1 silicon, it is required to upgrade to 1.16.

@CadmusJiang and @zhouqiang-cl are in charge for upgrading Go version to 1.16 and most of validation works are done manually. Hopefully we get it done in this month.

This also supports TiDB stacks to upgrade Go version to 1.16 pingcap/tidb#22198

[CadmusJiang]

Get go1.16 image: docker pull hub.pingcap.net/pingcap/centos7_golang-1.16:latest

[lichunzhu]

fixed in #286