Switch from TravisCI to GitHub Actions

[dbrgn]

Switch from TravisCI to GitHub Actions.

Also, deprecate Python 3.4 to get rid of some hacks in the CI script. Python 3.4 EOL has been reached in 2019. The current code should still work on 3.4, but there will be no more CI checks, so it may break in the future.

Coveralls has been replaced with Codecov due to easier integration.

[dbrgn]

Merging without a review, since this should be fairly uncontroversial.

[francium]

Was just about to comment before the merge. I'll assume this isn't an issue:

I haven't looked into Github Actions, but is this right? Won't this cause pull requests not to get tests? I read this as whenever you push master, run a build, but do nothing on a pull_request being pushed too. I'm probably reading this wrong, but just wanna double check

This was in reference to, ci.yml

on:
  push:
    branches:
      - master
  pull_request:

[dbrgn]

@francium sorry, I was a bit impatient in order to get #27 merged 🙂

The config is correct, it will trigger CI on push to master, or on any pull request. The way it looks is just a peculiarity of the YAML file format, see this link for a parsed representation. It will result in pull_request: null but that just means that there's no configuration/constriant for the pull request trigger, but since the key is present it will still run.

The reason why I'm limiting pushes to master is that a push to a branch should not get tested twice (once due to the push and once due to being part of a PR). The only downside is that you'll need to open a PR for CI to run on a branch.

[francium]

No problem. I assumed you knew what you were doing.

Thanks for the explanation. Makes sense now that I look at it that way.