fix: 解决不支持透明度映射问题

[lvisei]

PR includes

• [ ] fixed #0
• [ ] add / modify test cases
• [ ] documents, demos

Screenshot

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[github-actions[bot]]

🎊 PR Preview 1dd8cdb08ba85f24ee40f77566ea8137731185ac has been successfully built and deployed to https://antvis-L7Plot-preview-pr-303.surge.sh

:clock1: Build time: 384.627s

_{🤖 By surge-preview}