fix(field): fix unexpected formatting

[dgmpk]

在 type 为 number 或 digit 时，如果没有设置 min 或 max，onblur 时值 1.00 不会有变化，但当设置了 min 或 max 时，onblur 会触发非必要的格式化，导致值 1.00 变成 1。

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.66%. Comparing base (ec5b45b) to head (f00a3d2).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/vant/src/field/Field.tsx	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13282      +/-   ##
==========================================
+ Coverage   89.60%   89.66%   +0.05%     
==========================================
  Files         257      257              
  Lines        7013     7014       +1     
  Branches     1736     1737       +1     
==========================================
+ Hits         6284     6289       +5     
+ Misses        384      380       -4     
  Partials      345      345              

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[inottn]

Could you please add a test for the case? Thanks.