Release v0.2.1

Changelog:

v0.2.1:
- Fixed test reliability by improving clone operation
  * Create repo2 directory explicitly
  * Initialize git repo
  * Use fetch and checkout instead of direct clone
  * Avoid issues with empty directories
- Fixed GPG environment setup in tests

v0.2.0:
- Major AWS SDK Migration
  * Migrated from rusoto to aws-sdk-rust
  * Improved AWS credential handling
  * Better S3 integration

- Build System Improvements
  * Added musl targets for x86_64 and aarch64
  * Updated GitHub Actions workflows
  * Improved release process

- Enhanced Logging and Error Handling
  * Added comprehensive logging with file name and line numbers
  * Improved git protocol logging
  * Better error handling for broken pipes
  * Log file output to /tmp/git-remote-s3.log

- Testing Improvements
  * Added integration-test target
  * Enhanced test logging and readability
  * Consolidated test scripts into Makefile
  * Better GPG encryption test coverage

- Code Quality
  * Updated to Rust 2021 edition
  * Converted to async/await pattern
  * Simplified error handling
  * Improved code organization

- Security
  * Enabled GPG encryption by default
  * Better GPG key management in tests
  * Improved security-related error messages