Manually building gh-ost on go1.16 requires special configuration

[natewernimont-wk]

As of go1.16, go modules are defaulted to be enabled. This means that any consumer manually packaging gh-ost needs to override GO111MODULE. Additionally, go modules are the now standard approach to dependency management in go. It would be nice to move to go modules.

[shlomi-noach]

My personal thoughts shared on the PR: #932 (comment)

[timvaillancourt]

@natewernimont-wk this is resolved with the merge of #966

Moving to go mod will continue in #966