Move ci from travis to github actions

[SumLare]

#162

Looks like Coveralls api is under maintenance right now, hopefully ci turns green after they finish

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[SumLare]

@googlebot I signed it!

[Jeffwan]

I can not remember the default behavior here. Without specifying the ref, does it by default

1. fetch HEAD for pull_request?
2. fetch master for push

[SumLare]

The branch, tag or SHA to checkout. When checking out the repository that
triggered a workflow, this defaults to the reference or SHA for that event.
Otherwise, uses the default branch.

[SumLare]

Ok yeah, as per docs:

1. pull_request -> Last merge commit on the GITHUB_REF branch (master)
2. push -> Commit pushed

[Jeffwan]

@SumLare Thanks for taking this story. Can you help look at the comments?

[Jeffwan]

Thanks for the contribution.

/lgtm
/approve

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Jeffwan

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