Currently the test dependencies and configuration is left behind, compared to plugins.

Tasks

• Update composer dev dependencies to match plugins
• Sync phpcs configuration with plugins
• Fix any code errors that may come in surface by this change

Ref
master-theme
https://github.com/greenpeace/planet4-master-theme/blob/develop/composer.json
https://github.com/greenpeace/planet4-master-theme/blob/develop/phpcs.xml.dist
blocks
https://github.com/greenpeace/planet4-plugin-gutenberg-blocks/blob/develop/composer.json
https://github.com/greenpeace/planet4-plugin-gutenberg-blocks/blob/develop/phpcs.xml