[tests] Use Github Actions for tests

[bantic]

Note This is based on the 3.0-beta branch, not master.

Run tests at github actions. The open-source queue for the Travis tests is variable and sometimes the tests at travis are stuck in the queue for hours. Github Actions run much more quickly (and predictably).

Changes:

• ✂️ .travis.yml file
• Add .github/workflows/ci.yml
• Add a resolution on ember-compatibility-helpers@1.2.1 in the ember-try scenarios for 2.4 and 2.8 to work around a bug in 1.2.2 when the ember-source package is not present, see Latest version failed with error Cannot read property 'match' of undefined ember-cli/ember-compatibility-helpers#47

[jiayingxu]

🚀 Looks great! Switching to Github Actions will hugely improve developer productivity in ember-table.

[VelDeveloper]

@bantic Could you please elaborate this point a bit

Add a resolution on ember-compatibility-helpers@1.2.1 in the ember-try scenarios for 2.4 and 2.8 to work around a bug in 1.2.2 when the ember-source package is not present, see pzuraq/ember-compatibility-helpers#47

I am still struggling with this issue ....It would be really helpful if you elaborate a bit. I never used ember try. How it resolve my problem?

[bantic]

@VelDeveloper Sure thing — the resolution on ember-compatibility-helpers@1.2.1 ensures that the yarn install that ember-try runs will install that version of ember-compatibility-helpers even if some other of your dependencies themselves have a dependency on a new version of ember-compatibility-helpers.

You can read more about resolutions here: https://classic.yarnpkg.com/en/docs/selective-version-resolutions/

ember-try is a tool for testing ember addons against different versions of ember and probably not directly relevant to your issue: https://github.com/ember-cli/ember-try

I added some more details on the upstream issue, too: ember-cli/ember-compatibility-helpers#47 (comment)