fix: 修复 windows 下图片引入路径错误的问题

[Darmody]

fix #311

[vercel]

This pull request is being automatically deployed with ZEIT Now (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://zeit.co/yesmeck/remax/4bzstvbhz
🌍 Preview: https://remax-git-fix-win-import-image.yesmeck.now.sh

[codecov]

Codecov Report

Merging #312 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #312   +/-   ##
=======================================
  Coverage   89.96%   89.96%           
=======================================
  Files         174      174           
  Lines        2133     2133           
  Branches      282      282           
=======================================
  Hits         1919     1919           
  Misses        213      213           
  Partials        1        1

Impacted Files	Coverage Δ
packages/remax-cli/src/build/rollupConfig.ts	95.94% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ce8239f...196cfc1. Read the comment docs.