feat: support sync mode for http response.

[appleboy]

fix #206
fix #127

[codecov-io]

Codecov Report

Merging #208 into master will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #208      +/-   ##
==========================================
+ Coverage    96.2%   96.25%   +0.05%     
==========================================
  Files          13       13              
  Lines         895      907      +12     
==========================================
+ Hits          861      873      +12     
  Misses         26       26              
  Partials        8        8

Impacted Files	Coverage Δ
config/config.go	100% <100%> (ø)	⬆️
gorush/notification.go	91.25% <100%> (+0.38%)	⬆️
gorush/server.go	100% <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 fcdd369...d2e5eff. Read the comment docs.