v2.3.0

Release v2.3.0

  Major improvements and fixes:

  Core Fixes:
  - Fixed critical XSS vulnerability in polyfill_filter_var_string()
  - Standardized all validator method signatures for PHP 8+ compatibility
  - Fixed PHP 7.1 compatibility issues (assertIsArray, German umlaut tests)

  Testing:
  - Added comprehensive test coverage for missing validators and filters
  - Created 5 new test files with 100+ additional test cases
  - Fixed all PHPUnit configuration issues for cross-version compatibility

  Documentation:
  - Updated README with complete validator/filter documentation (41 validators, 16 filters)
  - Added CI-compatible documentation generation system
  - Comprehensive real-world usage examples

  CI/CD:
  - Enhanced coverage reporting with dynamic PHPUnit config generation
  - Added cross-version compatibility scripts for PHP 7.1-8.4+
  - Improved Coveralls integration with graceful fallbacks

  Security:
  - Fixed string sanitization vulnerability
  - Enhanced XSS protection in filter methods
  - Secure by default configuration improvements

  All tests passing: 440 tests, 489 assertions ✅