fix: 修复热力图颜色映射错误

[lxfu1]

• tests

现状： https://g2plot.antv.vision/zh/examples/heatmap/basic#shape

修复态：

[github-actions]

😭 Deploy PR Preview af41c00 failed. Build logs

_{🤖 By surge-preview}

[coveralls]

Pull Request Test Coverage Report for Build 375709923

• 2 of 2 (100.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.06%) to 96.558%

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Files with Coverage Reduction	New Missed Lines	%
src/utils/transform/word-cloud.ts	2	98.31%

Totals
Change from base Build 375593577:	-0.06%
Covered Lines:	3938
Relevant Lines:	3975

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💛 - Coveralls

[hustcc]

求单测，bugfix的单测比 feat 单测更重要，碰上就可能是线上 bug。