fix: setConfig uppercase strings

[ycjcl868]

Close #3866.

Checklist

• npm test passes
• tests are included
• documentation is changed or added
• commit message follows commit guidelines

Description of change

• any feature?
• close https://github.com/umijs/umi/ISSUE_URL

[netlify]

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[ycjcl868]

/rebase

[codecov]

Codecov Report

Merging #3868 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #3868   +/-   ##
=======================================
  Coverage   40.54%   40.54%           
=======================================
  Files         283      283           
  Lines        8010     8010           
  Branches     1886     1937   +51     
=======================================
  Hits         3248     3248           
+ Misses       4388     4381    -7     
- Partials      374      381    +7

Impacted Files	Coverage Δ
...build-dev/src/plugins/commands/config/setConfig.js	100% <100%> (ø)	⬆️
...kages/umi-plugin-ui/src/plugins/dashboard/index.ts	0% <0%> (ø)	⬆️
...s/umi-build-dev/src/plugins/commands/block/util.ts	33.11% <0%> (ø)	⬆️
packages/umi-plugin-ui/src/bubble/index.jsx	0% <0%> (ø)	⬆️

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