feat: support ubuntu-22.04 install

[younke]

Add Ubuntu 22.04 Support

Summary

This PR adds support for installing Sourcery on Ubuntu 22.04 LTS systems.

Changes

lib/utils.bash

• Added get_platform() - Detects the current platform by checking uname -s and parsing /etc/os-release on Linux

  • Returns macos for Darwin systems
  • Returns ubuntu-22.04 for Ubuntu 22.04 systems
  • Fails with clear error on unsupported systems

• Added get_ubuntu_asset_url() - Dynamically fetches the Ubuntu release asset URL from the GitHub API

  • Detects processor architecture via uname -m (supports x86_64, aarch64)
  • Matches assets with pattern *ubuntu*22.04*{arch}*.tar.xz
  • Returns the browser_download_url from the release assets

• Updated download_release() - Uses platform-specific download URLs:

  • macOS: sourcery-{version}.zip
  • Ubuntu: dynamically resolved from GitHub API

bin/download

• Added platform detection to select correct archive extension (.zip vs .tar.xz)
• Added platform-specific extraction commands:
  • macOS: unzip
  • Ubuntu: tar -xf

.github/workflows/build.yml

• Extended CI to use matrix strategy, running plugin tests on both macos-latest and ubuntu-22.04

Why Dynamic URL Resolution?

The Ubuntu asset naming varies across Sourcery releases (e.g., ubuntu-22.04.4 in 2.2.5 vs ubuntu-22.04.5 in 2.2.6). Instead of hardcoding the asset name, we query the GitHub API to find the correct download URL for each version.

Limitations

• Only Ubuntu 22.04 is supported on Linux
• Other Linux distributions will fail with a clear error message

Testing

• shellcheck passes
• CI passes on macOS
• CI passes on Ubuntu 22.04