1.9.0

v1 minor release

• Add support for Ubuntu 20.04 runners. Refer to the docs.
• Add support to specify composer version in tools input. Refer to the docs.
• Update actions/cache uses to v2.
• Pre-install PCOV with PHP 8.
• Switch from xz to zstd compression for packaging PHP 8.0.
• Decouple script for PHP 8.0 on Linux.
• Fix updating powershell profiles on Windows.
• Improve documentation.
• Refactor internal testing workflows.
• Revert to ES2019 as Node 12.x is the default version.
• Cleanup ESlint config.
• Update Node dependencies.