fix(comp:tour): async appended steps doesn't work

[sallerli1]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

在 tour 组件实例创建之后异步添加的step，不能正常显示

What is the new behavior?

修复以上问题

Other information

[idux-bot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.19%. Comparing base (a50147b) to head (9437a4f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1866   +/-   ##
=======================================
  Coverage   91.19%   91.19%           
=======================================
  Files         349      349           
  Lines       34269    34269           
  Branches     2767     2767           
=======================================
  Hits        31250    31250           
  Misses       3019     3019           

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