Expand CI coverage and tighten execution

[KentarouTakeda]

Overview

• Added 8.2 and 8.3 to the php version to be tested in CI.
• Fixed test failure on php-8.1 and later by using phpunit according to php version and officially added to CI.

Detail

A detailed step-by-step explanation of all the fixes made in this pull request.

1. 3472e1e : Added 8.1, 8.2, 8.3 to the php version to be tested.
   • All tests now fail on php 8.1 and later, which were previously marked as experimental. Here are the results.
   • This is because phpunit:^7 installed with --prefer-lowest does not support php-8.1 or later.
2. a048521 : Use different versions of phpunit depending on the php version to be tested.
   • With this fix, all tests that previously failed now pass.
   • So far, most of the issues have been resolved, but the CI results are showing many warning messages below. Here are the results.

     The following actions uses node12 which is deprecated and will be forced to run on node16: shivammathur/[email protected], actions/checkout@v2.

3. fdd7d09 : Use the latest version of setup-php.
   • All CI warning messages have disappeared. Here are the results.
4. UPDATE: 2024-01-04 11:15 JST c372bc3 Adjusted the way to specify dependencies to pass the Scrutinizer CI (installed version remains the same)

Motivation

According to Packagist usage statistics, more than 90% of the versions of php currently installed with this library are 8.1 or later. Testing on real versions will improve reliability.

These tests may also be required when changing the version of dependent libraries. This is because the updated version is likely to use a newer PHP version.

For example, the following pull request also suggests a broader version dependency:

• Add support to psr/http-message 2.0 #213

[KentarouTakeda]

Adjusted the way dependencies are specified to pass the Scrutinizer CI. Ready for review.