docs: added security policy

[JonasDevDE]

This pull request introduces a new SECURITY.md file to establish a formal security policy for the project. It includes details about supported versions, vulnerability reporting procedures, and encryption methods for secure communication.

Key additions:

Security Policy

• Added a section outlining supported versions, indicating that security updates are only provided for the most recent version.

Vulnerability Reporting

• Included instructions for reporting vulnerabilities, emphasizing responsible disclosure, response times, and the availability of a bounty program for eligible reports.

Secure Communication

• Provided details on encrypting emails using a PGP Public Key, including the key ID, fingerprint, expiration date, and the full public key block.