Add goang 1.16.x to the matrix build

[kishaningithub]

No description provided.

[coveralls]

Coverage remained the same at 92.056% when pulling 3d26fcc on kishaningithub:patch-1 into 2fee6af on go-stack:master.

[ChrisHines]

Thanks for the PR! But it will need some changes to make it right. Let me explain ....

For better or worse, I've been using the git-flow branching model on this project. I picked that approach back when this package was pretty new and Go modules didn't exist yet. It had the benefit of only merging to the master branch when I tagged a new release, which meant that the default go get behavior in those pre-modules days resulted in people only getting the latest tagged release. Obviously that is less valuable now, but the newest code in this repo is still on the develop branch which only gets merged to master when tagging a release.

So, to do this PR right it should start from the develop branch and also target the develop branch. You will find that the develop branch has a Github Actions based build instead of TravisCI. But Go 1.16.x is also missing from the Github Actions config, so it does need updating.

[kishaningithub]

@ChrisHines Thanks for the very detailed response! Have created the below PR on the develop branch to add go 1.16

#29

Closing this PR in favor of that one