fix: shadow style error when set width

[xrkffgg]

🤔 这个变动的性质是？/ What is the nature of this change?

• 新特性提交 / New feature
• bug 修复 / Fix bug
• 样式优化 / Style optimization
• 包体积优化 / Package size optimization
• 性能优化 / Performance optimization
• 代码风格优化 / Code style optimization
• 其他 / Other

🔗 相关 Issue / Related Issue

💡 需求背景和解决方案 / Background or solution

[github-actions]

🎊 PR Preview aab792e has been successfully built and deployed to https://image-tool-react-image-shadow-preview-pr-7.surge.sh

🕐 Build time: 191.739s

_{🤖 By surge-preview}

[codecov]

Codecov Report

Merging #7 (aab792e) into main (0ff40ab) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main        #7   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines            8         8           
  Branches         4         4           
=========================================
  Hits             8         8           

Impacted Files	Coverage Δ
src/image-shadow.tsx	100.00% <ø> (ø)

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[github-actions]

Size Change: -27 B (1%)

Total Size: 2.07 kB

Filename	Size	Change
./dist/index.esm.js	871 B	-14 B (1%)
./dist/index.js	967 B	-13 B (1%)

ℹ️ View Unchanged

Filename	Size	Change
./dist/index.css	235 B	0 B

_{compressed-size-action}