* Add GO111MODULE=off to build.sh
* Use golang 1.16
* Update go version in README.md
* Add missing GO111MODULE=off
* Add missing GO111MODULE=off again
* Use go1.16.3 explicitly
* Use 1.16 for CI test
* Update min go version
* Use go 1.16.4
GitHub CI/CD is [a thing](https://github.com/features/actions)! We will attempt:
- CI: build + unit test
- replica tests: running `gh-ost` tests on multiple MySQL versions