refactor: skip d.ts files when doctor parsing

[PeachScript]

doctor 在收集源代码文件的时候过滤掉 .d.ts 文件，两个原因：

1. doctor 预期是只查 JavaScript 和 TypeScript 源代码，类型文件不在目前的设计内
2. esbuid 对 .d.ts 文件内容的报错不如 tsc 人性化，不如交给 IDE 或交给 build 来提示

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (2150873) 93.81% compared to head (8f51cc6) 93.81%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #700   +/-   ##
=======================================
  Coverage   93.81%   93.81%           
=======================================
  Files          54       54           
  Lines        1537     1537           
  Branches      365      365           
=======================================
  Hits         1442     1442           
- Misses         90       95    +5     
+ Partials        5        0    -5     

Files Changed	Coverage Δ
src/doctor/index.ts	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

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