Switch primary branch from `master` to `main`

[aparlato]

This repo uses master as its primary branch. Let's go ahead and switch over to main.

@ebrelsford this is definitely low priority, but I think you may have to take this on due to permissions since I can't see branch settings.

[ebrelsford]

This will also require changing / removing the copy-to-s3 behavior, since it writes to an S3 bucket at dist/{{ env.BRANCH_NAME }} and could overwrite dist/main...

[aparlato]

Ah this is a great point. I think it makes the most sense to remove that Github Action here since this is now a module and is not specific to the Amazon project bucket where this is currently getting copied.

We can copy this to S3 from the Amazon repo (and make whatever other hardcoded link changes we need). I think we can technically copy it from the module import if we don't exclude it or we could have the standalone tool live in that repo.

@ebrelsford what do you think makes sense?

[ebrelsford]

main is the default branch now.