Dev: PHP 8.3 support

[kenjis]

https://wiki.php.net/todo/php83

• add PHP 8.3 to GitHub Action checks
  • chore: add PHP 8.3 to test-phpunit.yml #7886
• ReflectionProperty::setValue() signature deprecation
  • See Add note about ReflectionProperty::setValue() signature deprecation to upgrade guide php/php-src#12036
  • [PHP 8.3] refactor: ReflectionProperty::setValue() signature deprecation #7911
• [n/a] get_class() and get_parent_class() function calls without arguments deprecated
• [n/a] unserialize(): Upgrade E_NOTICE errors to E_WARNING
• highlight_file and highlight_string output HTML changes
  • [PHP 8.3] test: update expectation for highlight code #7912
  • Displaying Error Page with 4.4 with PHP 8.3 #8398
• [n/a] Granular DateTime Exceptions
• [n/a] Class constant type declarations in some PHP extension classes
• [n/a] Built-in CLI Server $_SERVER['SERVER_SOFTWARE'] value changed for RFC3875 compliance
• [n/a] Dependent packages
• Update highest versions to 8.3 in GitHub Action flows
• Update Issue Template chore: add PHP 8.3 to the bug report template #8404

References:

• https://php.watch/versions/8.3
• https://wiki.php.net/rfc/deprecations_php_8_3
• Dev: PHP 8.2 support #6170