Add Github Actions

[danon]

Rationale:

• From Travis CI: https://www.jeffgeerling.com/blog/2020/travis-cis-new-pricing-plan-threw-wrench-my-open-source-works
  From now on, Travis CI offers 10000 credits to all free-tiers (per user), and they aren't renewed (so it's 10000 credits for life). After they reach 0, builds simply stop running. In my T-Regx library I already lost 1000 credits :/ You can pay to get more credits.
  You can see here: https://travis-ci.com/account/plan how much credits you have left.
• On the other hand, GithubActions gives you unlimited builds for public repositories (2000 minutes of CPU time per month for private repositories)

As long as they both work, you can keep them both, to see which do you prefer.

PR Overview:

• I used docker images for databases:
  • For MySQL: hub.docker.com/mysql:8
  • For PostgreSQL: hub.docker.com/postgres:10.0
  • Probably using alpine images or different versions will be easy. Just edit image field.
  • Databases are seeded from proper file from test/test-db/recreate_schema.sql
  • Both of them use db:ouzo_test and creds:ouzo_user/password
  • Fun note: Github configuration is 1:1 docker params. So you can recreate the workflow locally 1:1 (if you have docker). The results in the Github Actions were exactly the same as I had them using docker and phpunit locally.
  • You can't do mysql/psql, you must do mysql -h 127.0.0.1, psql -h 127.0.0.1 (or localhost). You must do the same if you run mysql/postgres in docker locally - another reason why ghActions is 1:1 local docker.
• I recreated the matrix from Travis (['PHP 8.0.0', 'PHP 8.0.1'] x ['MySQL', 'PostgreSQL', 'SQLite'])
• I used actions/cache@v1 action, so that composer dependencies aren't loaded each time (speeds up the build)
• ./vendor/bin/php-coveralls is run at the end of the workflow, so coverage can be used by coveralls
• I used echo | sqlite to seed SQLite base, because sqlite db -init file.sql opened prompt for stdin, so.
• I tried to seed the MySQL database as ouzo_user user, but I was getting error, failing at CREATE FUNCTION get_name, line 39:

  You do not have the SUPER Privilege and Binary Logging is Enabled
  

  so I used superuser -u root -ppassword to seed it. Perhaps there's a way to seed and create function as a regular user, but I didn't find it.
• phpunit is run with proper db env variable required by config/test/config.php, as well as proper @group

  matrix:
    php: [ '8.0.0', '8.0.1' ]
    db: [ 'MySQL', 'PostgreSQL', 'SQLite' ]
    include:
      - db: MySQL
        phpunitArgs: "--exclude-group postgres,sqlite3"
        phpunitEnv: db=mysql # from config/test/config.php
      - db: PostgreSQL
        phpunitArgs: "--exclude-group mysql,sqlite3"
        phpunitEnv: db=postgres # from config/test/config.php
      - db: SQLite
        phpunitArgs: "--exclude-group mysql,postgres,non-sqlite3"
        phpunitEnv: db=sqlite3 # from config/test/config.php

• I added a badge for the build in ReadMe.me
  

[bbankowski]

Looks good, thanks @danon!

[danon]

@bbankowski If you decide to stop using Travis, just revert the last commit in this PR, 1b262bb