Replace CI on Travis and AppVeyor with GitHub Actions

[jacobtomlinson]

CI has been pretty slow lately.

This is a test to see how easy it would be to switch our CI to GitHub Actions for more parallelism and hopefully less queueing.

[jacobtomlinson]

Ok this seems to work pretty nicely. I'm inclined to merge this and disable Travis and AppVeyor completely.

Before I do it would be good to get some thoughts from the other maintainers.

[FabioRosado]

This looks so great! I really want to dig into github actions and this PR made me want to play around with them even more! I'm pretty happy to ditch Travis, it has served us well but yeah we are having a lot of issues with it. Not only it takes a long time to run sometimes it doesn't report the status to github and things just stay untouched until something unstucks the report (still dont know why or how)

So disabling travis I'm up for it. Appveyor doesn't bother me, but we had it because of the windows compatibility, if we ditch appveyor will we risk of breaking opsdroid on windows? Also is opsdroid working 100% on windows to even matter? 🤔

[jacobtomlinson]

Yeah Travis has been causing enough problems that I'm ready to try something else.

GitHub Actions also runs on Windows and MacOS. So we should be better off!

[FabioRosado]

Oh awesome! Then yeah I'd say move the whole thing to github actions should be easier to maintain as well 👍

[codecov]

Codecov Report

Merging #1472 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1472   +/-   ##
=======================================
  Coverage   99.90%   99.90%           
=======================================
  Files          52       52           
  Lines        3186     3276   +90     
=======================================
+ Hits         3183     3273   +90     
  Misses          3        3           

Impacted Files	Coverage Δ
opsdroid/web.py	100.00% <0.00%> (ø)
opsdroid/core.py	100.00% <0.00%> (ø)
opsdroid/loader.py	100.00% <0.00%> (ø)
opsdroid/message.py	100.00% <0.00%> (ø)
opsdroid/cli/logs.py	100.00% <0.00%> (ø)
opsdroid/cli/start.py	100.00% <0.00%> (ø)
opsdroid/cli/config.py	100.00% <0.00%> (ø)
opsdroid/cli/version.py	100.00% <0.00%> (ø)
opsdroid/constraints.py	100.00% <0.00%> (ø)
opsdroid/cli/__init__.py	100.00% <0.00%> (ø)
... and 15 more

---

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