[Tests] migrate travis-ci to Github Actions

[ljharb]

travis seems dead.

[ljharb]

Crap, unfortunately this won't run until some workflow is merged to master. See #339.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@4b6e9df). Click here to learn what that means.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             master      #338   +/-   ##
==========================================
  Coverage          ?   100.00%           
==========================================
  Files             ?         9           
  Lines             ?       181           
  Branches          ?         0           
==========================================
  Hits              ?       181           
  Misses            ?         0           
  Partials          ?         0           

Impacted Files	Coverage Δ
src/bin/find.js	100.00% <100.00%> (ø)
src/lib/cli-util.js	100.00% <100.00%> (ø)
src/lib/rule-finder.js	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4b6e9df...bc91e07. Read the comment docs.

[ljharb]

I think these test failures are likely legitimate - altho they might be related to our use of proxyquire in tests.

The only remaining test failures are "timeout" ones. They all seem to fail consistently (and I can reproduce locally) in node 10 or below.

We can't (and shouldn't) drop support for that, but we might still choose to make those optional so this can get landed. Thoughts? @jfmengels @sarbbottam @ta2edchimp