fix: 兼容实际屏幕宽度为小数的情况

[guoenxuan]

这个 PR 做了什么? (简要描述所做更改)

这个 PR 是什么类型? (至少选择一个)

• 错误修复(Bugfix) issue: fix #
• 新功能(Feature)
• 代码重构(Refactor)
• TypeScript 类型定义修改(Typings)
• 文档修改(Docs)
• 代码风格更新(Code style update)
• 其他，请描述(Other, please describe):

这个 PR 涉及以下平台:

• 所有小程序
• 微信小程序
• 支付宝小程序
• 百度小程序
• 字节跳动小程序
• QQ 轻应用
• 京东小程序
• 快应用平台（QuickApp）
• Web 平台（H5）
• 移动端（React-Native）
• 鸿蒙（harmony）

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.51%. Comparing base (80b7616) to head (5543fba).
Report is 54 commits behind head on main.

❗ Current head 5543fba differs from pull request most recent head 215ea52. Consider uploading reports for the commit 215ea52 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15435      +/-   ##
==========================================
- Coverage   58.52%   58.51%   -0.02%     
==========================================
  Files         491      491              
  Lines       21883    21891       +8     
  Branches     5621     5624       +3     
==========================================
+ Hits        12808    12810       +2     
- Misses       7891     7897       +6     
  Partials     1184     1184              

Flag	Coverage Δ
taro-cli	63.29% <ø> (-0.38%)	⬇️
taro-runner	46.25% <ø> (ø)
taro-runtime	65.35% <ø> (ø)
taro-web	40.28% <ø> (ø)

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see 3 files with indirect coverage changes