Add release 0.3 JAR file

Changelog for Backup-Finder v0.3
New Features:
Dynamic Payload Generation: Enhanced the algorithm for dynamic payload generation, allowing for more adaptive and targeted scanning based on the web application's structure and content.
Improved File Extension Handling: Expanded the list of file extensions in the scanning process to include modern and less common formats, providing broader coverage and detection capabilities.
Enhancements:
Updated backup_zipFiles Content: Augmented the backup_zipFiles with additional entries related to development environments, database dumps, and cloud service configurations, significantly improving the tool's ability to detect sensitive backup files.
Enhanced dir_commonFiles and root_commonFiles Lists: Expanded these lists to include a wider range of common files and directories that may contain sensitive information, offering a more thorough scanning process.
Community and Contribution:
Added guidelines for community contributions, including how to report bugs, suggest features, and submit code changes, fostering a collaborative improvement environment.