Replace Travis CI with GitHub Actions workflows

[schlessera]

No description provided.

[jrfnl]

Suggested change

	- name: Set up PHP envirnoment
	- name: Set up PHP environment

(here and everywhere else)

[jrfnl]

Had a quick look through what is here so far (this is not a full review).

• You may want to have a look at the ramsey/composer-install action - this will save on a lot of duplication with the composer install/composer caching.
• IMO the lint action should be run - at least - on the lowest + highest supported PHP version.
  For a library like this which is used as a dependency for other projects, I'd even go so far as to run it on all supported PHP versions just to be sure.
• Pro-tip: for the lint action, exclude the .git directory.
  This is not excluded by default in Parallel Lint and for "old" projects, not excluding it can really slow the action down a lot as the script will search the whole .git directory for PHP files.
  Oh and for this repo, you may also want to exclude the docs directory, though that shouldn't make much difference.
• Suggestion: add a lint script to the composer.json file to make it easy for people to run the linting locally with the correct parameters:

  "lint": [
    "@php ./vendor/php-parallel-lint/php-parallel-lint/parallel-lint . -e php --exclude vendor --exclude .git
  ],

  Note:
  • the @php is to make sure the same PHP version is used as used by Composer (instead of a default PHP version on a system);
  • the full path name is for improved compatibility cross-platform (i.e. make sure it also works on Windows).
• I hadn't come across the cs2pr usage before, but if it does what I expect it to do, I like it 👍
  Will have to nick that trick and apply it to various workflows in other projects 😉
• I generally prefer to run the QA checks against all pushes, not just master, though for the tests - depending on how complex the matrix is - I sometimes use a simpler, only high/low job for pushes.
  Providing people check the action outcome before opening a PR, it should prevent PRs being opened which don't pass on the basics, which then have to get a second commit/force push to fix the PR as soon as it's opened.
• You can add PHP 8.1 to the matrix for the unit job to test against the current PHP nightly.
  Use it in combination with continue-on-error to prevent it from failing/stopping the workflow run.
• Once the script is finished, you may want to remove the fail-fast: false to be kind to the GH resources.

[jrfnl]

Just making a note here that this PR would close #420 + #439

[jrfnl]

Oh and another reminder: let's not forget to update the badges in the Readme once this PR is ready.

[jrfnl]

I'm moving this back to the 2.0.0 milestone as we do still seem to be able to view the Travis runs, which allows us to release 1.8.0 knowing that CI is passing, so we can leave this until after the 1.8.0 release.

[schlessera]

Closing this for now, as it is being superseded by #467