fix: 浮点数精度丢失导致画布缩放卡死

[ch1ny]

Description

在 mousewheel 计算下一个缩放尺寸时，会因为js浮点数计算问题导致缩放尺寸计算存在误差：

• 即在缩小画布时，会计算出增大画布的缩放比例；
• 在放大画布时，会计算出缩小画布的缩放比例

Motivation and Context

在某些特定情况下，会导致画布的缩放比例被卡在某两个值之间来回切换，导致画布无法进行缩放。

#4168

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Enhancement (changes that improvement of current feature or performance)
• Refactoring (changes that neither fixes a bug nor adds a feature)
• Test Case (changes that add missing tests or correct existing tests)
• Code style optimization (changes that do not affect the meaning of the code)
• Docs (changes that only update documentation)
• Chore (changes that don't modify src or test files)

Self Check before Merge

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[x6-bot]

👋 @ch1ny

💖 Thanks for opening this pull request! 💖

Please follow the contributing guidelines. And we use semantic commit messages to streamline the release process.

Examples of commit messages with semantic prefixes:

• fix: don't overwrite prevent_default if default wasn't prevented
• feat: add graph.scale() method
• docs: graph.getShortestPath is now available

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 10.34%. Comparing base (a431f52) to head (5d118d6).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4356   +/-   ##
=======================================
  Coverage   10.34%   10.34%           
=======================================
  Files         180      180           
  Lines       10582    10582           
  Branches     2580     2580           
=======================================
  Hits         1095     1095           
  Misses       9398     9398           
  Partials       89       89           

Flag	Coverage Δ
x6	10.34% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
packages/x6/src/graph/mousewheel.ts	7.27% <0.00%> (ø)

[x6-bot]

👋 @ch1ny

Congrats on merging your first pull request! 🎉🎉🎉