Update postiz.yaml

[dr-diffie]

Proposed Improvements to Postiz Template

I'd like to propose several improvements to the current Postiz template that enhance security, reliability, and configuration flexibility:

Security Enhancements

• Added Redis ACL configuration with proper authentication
• Implemented secure healthchecks with authentication
• Enhanced PostgreSQL security configurations

Reliability Improvements

• Added memory limits and resource management for Redis
• Implemented proper data persistence configurations
• Added tmpfs for temporary files
• More comprehensive healthcheck configurations with proper retry/timeout strategies
• Better dependency management with health conditions

Configuration Flexibility

• Support for all environment variables from Postiz documentation
• Added Cloudflare R2 integration support
• Logical grouping of environment variables
• Default values for critical settings
• Better volume management with explicit drivers

The improved template provides a more production-ready setup while maintaining compatibility with Coolify's requirements. It follows best practices for Docker deployments and provides better security out of the box.

Submit Checklist (REMOVE THIS SECTION BEFORE SUBMITTING)

• [ ] I have selected the next branch as the destination for my PR, not main.
• [ ] I have listed all changes in the Changes section.
• [ ] I have filled out the Issues section with the issue/discussion link(s) (if applicable).
• [ ] I have tested my changes.
• [ ] I have considered backwards compatibility.
• [ ] I have removed this checklist and any unused sections.

Changes

Issues

• fix #