The Travis CI appears to have been broken for a while. Also none of the CI services test Julia 1.5. This PR adds a single GitHub Actions CI workflow that tests the same cases as both Travis and Appveyor.
There are some failures. The 1.4 failures appear to be known. The 1.0 failure on ubuntu is a previously untested case (x86). So I'll go ahead and merge this.
The Travis CI appears to have been broken for a while. Also none of the CI services test Julia 1.5. This PR adds a single GitHub Actions CI workflow that tests the same cases as both Travis and Appveyor.