feat: support user agent for credentials requests

[yndu13]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 87.87879% with 4 lines in your changes missing coverage. Please review.

Project coverage is 80.11%. Comparing base (c424604) to head (973ed23).

Files	Patch %	Lines
alibabacloud_credentials/credentials.py	33.33%	2 Missing ⚠️
alibabacloud_credentials/providers.py	81.81%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #43      +/-   ##
==========================================
+ Coverage   79.90%   80.11%   +0.20%     
==========================================
  Files          17       17              
  Lines        1752     1770      +18     
==========================================
+ Hits         1400     1418      +18     
  Misses        352      352              

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