Feature: add reason phrase to response and exceptions

[yanyongyu]

related to #100

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 18.29%. Comparing base (9221b59) to head (a7f561b).

Files	Patch %	Lines
githubkit/response.py	66.66%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #101   +/-   ##
=======================================
  Coverage   18.28%   18.29%           
=======================================
  Files        4499     4499           
  Lines      234069   234075    +6     
=======================================
+ Hits        42809    42813    +4     
- Misses     191260   191262    +2     

Flag	Coverage Δ
unittests	18.29% <66.66%> (+<0.01%)	⬆️

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