adding github actions

[gingerlime]

• based on https://dev.to/pikachuexe/ruby-gems-ci-using-github-action-136o
• note that there's no direct equivalent to allow_failures
  see Please support something like "allow-failure" for a given job actions/runner#2347
  so there's only a workaround, which requires you to include specific
  combinations of the matrix ...
• removed old .travis.yml
• updated and fixed code and specs for fixes #58 handle ActionDispatch::Http::Parameters::ParseError #59
• TODO?:
  • check that coverage is similar to travis
  • refresh ruby / rails versions
  • deprecate some older versions

[gingerlime]

@yuki24 did you get a chance to take a look ? ;-)

[yuki24]

I've been busy these days and did not have time to do open source work. Please be patient until the dust gets settled...

[gingerlime]

I completely understand. Thank you.

[yuki24]

I have merged your commit fcd71ab in the other PR actions/toolkit#63. For some reason Actions is not running the builds with your workflow files so I started from scratch. I'm not sure why something fixed it.

The other change I made is to extract Rails edge and Ruby edge builds out of the big build config:

rambulance/.github/workflows/tests.yml

Lines 71 to 110 in 1b01aad

	rails_edge:
	strategy:
	matrix:
	ruby_version:
	- '3.0'
	- '2.7'
	gemfile:
	- gemfiles/rails_edge.gemfile
	runs-on: ubuntu-18.04
	env:
	BUNDLE_GEMFILE: ${{ matrix.gemfile }}
	steps:
	- uses: actions/checkout@v2
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby_version }}
	bundler-cache: true
	- run: bundle exec rake
	ruby_edge:
	strategy:
	matrix:
	ruby_version:
	- 'ruby-head'
	gemfile:
	- gemfiles/rails_edge.gemfile
	- gemfiles/rails_61.gemfile
	- gemfiles/rails_60.gemfile
	runs-on: ubuntu-18.04
	env:
	BUNDLE_GEMFILE: ${{ matrix.gemfile }}
	steps:
	- uses: actions/checkout@v2
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby_version }}
	bundler-cache: true
	- run: bundle exec rake || echo "Ruby edge test is done."

This way we don't have to worry about misconfigurations for the stable builds that are more important.

Thanks for the help! Really appreciated.