Handle <!-- comments --> in ATTRIBUTE-VALUE-XHTML/THE-VALUE tags

What's Changed

• chore(.github): switch the macOS job to macos-latest by @stanislaw in #207
• fix(lxml): improve lxml_stringify_node() to handle by @stanislaw in #206
• Bump version to 0.0.48 by @stanislaw in #208

Full Changelog: 0.0.47...0.0.48