Provide support for PHP 8.0

[ittmann]

Adds support for PHP 8.0 as requested in #27

• composer.json already doesn't support PHP less than 7.3
• composer.json currently does not require-dev phpunit
  (it is installed during initial project creation when MVC testing support is installed as described in README.md)
• no .travis.yml is present

Tested in docker with php:8.0-rc-apache
The skeleton app is compatible/runs without any issues.

phpunit reports an error on the use of the deprecated function libxml_disable_entity_loader in laminas-test, which should be fixed when PHP 8.0 support is added to laminas-test

 composer run test
> phpunit
PHPUnit 9.4.2 by Sebastian Bergmann and contributors.

Warning:       Your XML configuration validates against a deprecated schema.
Suggestion:    Migrate your XML configuration using "--migrate-configuration"!

.E.                                                                 3 / 3 (100%)

Time: 00:00.028, Memory: 10.00 MB

There was 1 error:

1) ApplicationTest\Controller\IndexControllerTest::testIndexActionViewModelTemplateRenderedWithinLayout
Function libxml_disable_entity_loader() is deprecated

/var/www/vendor/laminas/laminas-dom/src/Document.php:234
/var/www/vendor/laminas/laminas-dom/src/Document.php:159
/var/www/vendor/laminas/laminas-dom/src/Document/Query.php:45
/var/www/vendor/laminas/laminas-test/src/PHPUnit/Controller/AbstractHttpControllerTestCase.php:386
/var/www/vendor/laminas/laminas-test/src/PHPUnit/Controller/AbstractHttpControllerTestCase.php:411
/var/www/vendor/laminas/laminas-test/src/PHPUnit/Controller/AbstractHttpControllerTestCase.php:434
/var/www/vendor/laminas/laminas-test/src/PHPUnit/Controller/AbstractHttpControllerTestCase.php:451
/var/www/module/Application/test/Controller/IndexControllerTest.php:48

ERRORS!
Tests: 3, Assertions: 6, Errors: 1.
Script phpunit handling the test event returned with error code 2

[froschdesign]

@ittmann

phpunit reports an error on the use of the deprecated function libxml_disable_entity_loader in laminas-test, which should be fixed when PHP 8.0 support is added to laminas-test

libxml_disable_entity_loader is used in laminas-dom and this supports now PHP 8.

[samsonasik]

this may need laminas-skeleton-installer to support php 8 first, ref laminas/laminas-skeleton-installer#19

[samsonasik]

@ittmann please update laminas/laminas-skeleton-installer require to ^0.3 in composer.json. Thank you.

[ittmann]

Tested again (in docker with php:8.0-apache) after the version changes suggested by samsonasik dc82d2c
composer install with minimal install option works fine and the application runs without any issues.

Choosing MVC testing support or installing laminas-test after initial project creation fails (PHP 8.0 support hasn't been added to laminas-test yet)

Everything works as expected with php:7.3-apache / the current project Dockerfile and docker-compose.yml

[samsonasik]

There are extra components that need to be check against php 8, but for basic installation, I think it is ready 👍

[samsonasik]

I am merging it now, I will verify the latest components inside "extra" config.

[samsonasik]

Thank you @ittmann