Fix: 配置项无法使用字段名填写

[yanyongyu]

fix #94

[github-actions]

🚀 Deployed on https://deploy-preview-96--adapter-onebot.netlify.app

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 66.92%. Comparing base (e05d92c) to head (f8716ce).

Files	Patch %	Lines
nonebot/adapters/onebot/v11/config.py	77.77%	2 Missing ⚠️
nonebot/adapters/onebot/v12/config.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #96      +/-   ##
==========================================
- Coverage   66.96%   66.92%   -0.04%     
==========================================
  Files          24       24              
  Lines        2146     2156      +10     
==========================================
+ Hits         1437     1443       +6     
- Misses        709      713       +4     

Flag	Coverage Δ
unittests	66.92% <71.42%> (-0.04%)	⬇️

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