Support PHP 8.2 and newer #68

Problem

pekral/phpcs-rules declares "php": "^8.4" in require. A project that still supports PHP 8.2 or 8.3 therefore cannot install it as a dev dependency on those versions: composer install fails to resolve on PHP 8.2/8.3 even with --no-dev, because Composer resolves require-dev while locking.

PHP 8.2 and 8.3 are still officially supported (security fixes) — see https://www.php.net/supported-versions.php.

Real case: ecomailcz/flexibee-client supports PHP ^8.2. Its CI can run the pekral checkers only on PHP 8.4/8.5, and on 8.2/8.3 it is limited to a syntax lint plus a dev-free dependency resolve (Ecomailcz/flexibee-client#48).

Proposal

Lower the PHP requirement of pekral/phpcs-rules to ^8.2 so it can be installed in any project running a currently supported PHP version.

Acceptance criteria

• composer.json require.php is ^8.2.
• Every runtime dependency in require resolves on PHP 8.2 and 8.3. Development-only tooling may keep needing a newer PHP, but it must not block consumers.
• The shipped code uses no syntax or API newer than PHP 8.2, for example property hooks, asymmetric visibility, new without parentheses, typed class constants, #[\Override] or json_validate().
• CI covers PHP 8.2 and 8.3, at least a lint of the shipped sources and a resolve of the runtime dependencies. A full run is preferable where the dev tooling allows it.
• The README requirements section lists PHP 8.2+.