using travis.com for building x86

[mattip]

The project is still using travis.com for building on x86. This burns up our open source credits. Building on non-x86 architectures is free, but x86 builds should move to github actions or azure. I have requested more credits, but please modify the build system.

[mattip]

I have disabled the weekly cron job at https://app.travis-ci.com/github/MacPython/h5py-wheels/settings, which was failing. Please let me know if you wish to re-enable it.