PTHMINT-61: Add CHANGELOG.md (#4)

Author: zulquer

CHANGELOG.md

@@ -0,0 +1,26 @@
+# Changelog
+
+All notable changes to the MultiSafepay Python SDK will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [1.0.0rc1] - 2025-04-21
+
+### Added
+- Initial release candidate
+- Core API functionality
+- Support for payment methods
+- Order creation and management
+- Transaction handling
+- Webhook support
+- Comprehensive test suite
+- Type hints and documentation
+- Dependencies:
+  - Python >=3.8,<3.14
+  - requests ^2.32.3
+  - toml ^0.10.2
+  - pydantic ^1.10.0
+  - python-dotenv ^1.0.1