refactor: downgrade browser targets for swc transformer

[PeachScript]

降级 SWC 作为 transformer 时 browser 产物的 targets 为 { ie: 11 }，确保产物是 ES5，与 Babel 保持一致。

补充说明：esbuild 的 targets 之所以是 chrome 版本号，是因为很多高级语法它最多只能转换到 ES6，如果设置为 { ie: 11 } 会报错，但 SWC 有这个能力，所以没必要和 esbuild 一样使用 chrome 版本号

cc @MadCcc @huarse

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (8aa2415) 93.80% compared to head (d1fd0be) 93.80%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #689   +/-   ##
=======================================
  Coverage   93.80%   93.80%           
=======================================
  Files          54       54           
  Lines        1534     1534           
  Branches      345      364   +19     
=======================================
  Hits         1439     1439           
+ Misses         95       90    -5     
- Partials        0        5    +5     

Files Changed	Coverage Δ
src/builder/utils.ts	100.00% <ø> (ø)

... and 2 files with indirect coverage changes

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