Version 2.0.0-alpha1 / Update for PHPCompatibility 10.0.0-alpha1

[jrfnl]

This update accounts for the following changes:

• Ruleset:
  No ruleset updates needed.
• Composer:
  • Update the version for the PHPCompatibility dependency.
    The @dev version number suffix should ensure that the PHPCompatibility 10.0.0-alpha1 version can be installed, even if the project minimum stability does not specifically allow for dev versions.
  • Remove the DealerDirect Composer PHPCS plugin dependency.
    This plugin will now automatically be installed as it is a dependency of PHPCSUtils and therefore of PHPCompatibility itself.
    Not having it set as an explicit dependency here, will prevent potential future conflicts with the supported versions of the plugin.
  • Removed the suggest section.
    The DealerDirect plugin no longer needs to be suggested and after two years, people should have gotten the message about using the roave/security-advisories.
• Readme:
  • Updated the minimum PHP and PHPCS requirements.
  • Updated the installation instructions for the 2.0.0-alpha1 release (being a dev release).
  • Updated the installation instructions to no longer mention adding a Composer plugin to sort out the PHPCS installed_paths.
  • Added upgrade instructions.
  • Added section about funding.
  • Use link list for links used multiple times.
  • Minor other tweaks after critical read-through of the README.
• CI:
  • Continue testing against dev-develop.
  • Prevent builds failing on low PHP versions on the recommendation to use a more recent PHP version.