Migrate from Travis CI to GitHub Actions

[vfdev-5]

🚀 Feature

The idea is to migrate 3 following stages from Travis CI to GitHub Actions:

• Docs: https://github.com/pytorch/ignite/blob/master/.travis.yml#L64-L95
• Deploy: https://github.com/pytorch/ignite/blob/master/.travis.yml#L97-L145
• Nightly: https://github.com/pytorch/ignite/blob/master/.travis.yml#L147-L175 (done by Migrated nightly build/release to GitHub Actions (#1448) #1450)

Each stage can be a separate action: e.g. Docs -> .github/workflows/docs.yml, Deploy -> .github/workflows/binaries-release.yml, Nightly -> .github/workflows/binaries-nightly-release.yml

For PyDataGlobal contributors, feel free to ask questions for details if any and say that you would like to tackle the issue.
Please, take a look at CONTRIBUTING guide.

[ydcjeff]

@vfdev-5 docs and deploy left to done?
can i take this?

[vfdev-5]

@ydcjeff yes, docs and deploy are still open.
You can take a look at how to migrate docs, if you like. This task is also overlaps a little with this #1350 (it probably will be closed as stale) in the sense that I'd like to have "Nice to have" part for this issue.

[ydcjeff]

Okay, I will start working if that PR get closed.

[vfdev-5]

@ydcjeff #1350 does not solve the same problem. It will be closed once we migrated from Travis.

[ydcjeff]

Alright then I will draft a PR

[vfdev-5]

Thanks @ydcjeff !