feat(module: textarea): modify warp style

[sWhite01111]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd-mobile/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #379 into master will increase coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #379      +/-   ##
==========================================
+ Coverage   89.51%   89.58%   +0.07%     
==========================================
  Files         229      229              
  Lines        6894     6906      +12     
  Branches      564      564              
==========================================
+ Hits         6171     6187      +16     
+ Misses        558      554       -4     
  Partials      165      165

Impacted Files	Coverage Δ
...omponents/textarea-item/textarea-item.component.ts	98.75% <100%> (+0.1%)	⬆️
components/picker/picker.component.ts	81.97% <0%> (+1.74%)	⬆️
components/picker/picker.service.ts	94.44% <0%> (+5.55%)	⬆️

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