This release adds the support of node 16. npm will stop complaining about it:

npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: 'stylelint-config-property-sort-order-smacss@7.0.0',
npm WARN EBADENGINE   required: { node: '^10.0.0 || ^12.0.0 || ^14.0.0 || ^15.0.0' },
npm WARN EBADENGINE   current: { node: 'v16.5.0', npm: '7.20.3' }
npm WARN EBADENGINE }

Changelog: https://github.com/cahamilton/stylelint-config-property-sort-order-smacss/releases/tag/v7.1.0