fix: proxy post method should pass through the request data

[Jeff-Tian]

修复 eggjs/egg#3844

[codecov]

Codecov Report

Merging #18 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master      #18   +/-   ##
=======================================
  Coverage   77.27%   77.27%           
=======================================
  Files           4        4           
  Lines          22       22           
=======================================
  Hits           17       17           
  Misses          5        5

Impacted Files	Coverage Δ
app/controller/home.js	37.5% <0%> (ø)	⬆️

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