Add Github Action Integration

[KenFigueiredo]

Background: In order to improve the quality of our code base and more easily ensure that any change added to our codebase doesn't break it, we should add a Travis CI job to run terraform validate on any PR that is opened against master for Beekeeper-Terraform

The original target of this was to make this CI checks w/ Travis, however I figured since Github Actions is built in I may as well throw it out there as an option and see what everyone prefers

Note: This won't currently run on this repository until merged, but here is the result in my fork: KenFigueiredo#3

[KenFigueiredo]

Set AWS_DEFAULT_REGION as per hashicorp/terraform#21408 (comment) to not fail on implicit provider defaults.

[massdosage]

Nice, thanks for both PRs. Travis and GH actions look broadly equivalent. I'd be fine with going with either. One option would be to include them both for a while so we can compare them and then choose one and remove the other? Otherwise I'd have a slight leaning towards GH actions as they're seeing more and more adoption and are probably going to start taking over more from Travis since they're integrated directly with GH, supported by the Microsoft etc.

[KenFigueiredo]

Yeah that was my thought too. Since this is net new for this repository, I'd lean towards using only GH actions since we have Travis integrated on other repos. If we end up not liking it in the future, it's trivial to replace it with Travis.

The only other technical piece of this that I see being better than travis is that GH actions let you specify a docker image to build in so we don't need to include pulling & manually installing a terraform version as part of our prebuild setup. Depending on how their internals cache docker images could lead to faster build times.

[massdosage]

OK, let's get them both merged in an try run them in parallel for a while and then we can decide after a few cycles which to keep.