fix: field 计算autosize，需要nextTick

[pangxie1991]

• field 计算autosize，需要nextTick

[codecov-io]

Codecov Report

Merging #78 into dev will decrease coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##              dev      #78      +/-   ##
==========================================
- Coverage   81.91%   81.88%   -0.04%     
==========================================
  Files          82       82              
  Lines        1283     1286       +3     
  Branches      129      129              
==========================================
+ Hits         1051     1053       +2     
- Misses        188      189       +1     
  Partials       44       44

Impacted Files	Coverage Δ
packages/field/src/field.vue	80% <100%> (-1.82%)	⬇️

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