Released version 5.1.1

A quality-focused release that hardens dibi's type system and squashes a couple of real-world bugs.

🐛 Bug Fixes

• PostgreSQL – fixed a type error when passing null as the error code to createException() (#473)
• PHP 8.5 compatibility – Row::getIterator() now properly casts to array, and Result::normalize() handles null column types without triggering deprecation warnings (#467)
• Stricter null checking across Connection, DateTime, and Result – replaced loose ?: with ?? to avoid swallowing legitimate falsy values like 0

♻️ Code Refactoring

• Comprehensive native type improvements – added mixed, void, never, and union types (int|string) to method signatures across drivers, interfaces, and core classes
• Callable properties normalized to \Closure in HashMap and Result, making the internal type system more predictable
• Switched to singleline declare(strict_types=1) statements across all source and test files