refactor: modify the class name of credential model

[yndu13]

You need to complete

• unit tests and/or feature tests
• documentation is changed or added

[codecov-commenter]

Codecov Report

Merging #54 (cdf3090) into master (25c239d) will not change coverage.
The diff coverage is 90.00%.

❗ Current head cdf3090 differs from pull request most recent head 45a0fcb. Consider uploading reports for the commit 45a0fcb to get more accurate results

@@            Coverage Diff            @@
##             master      #54   +/-   ##
=========================================
  Coverage     84.69%   84.69%           
  Complexity      508      508           
=========================================
  Files            44       44           
  Lines          1784     1784           
  Branches        113      113           
=========================================
  Hits           1511     1511           
  Misses          236      236           
  Partials         37       37           

Flag	Coverage Δ
unittest	84.69% <90.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...edentials/provider/DefaultCredentialsProvider.java	81.25% <ø> (ø)
...entials/provider/EcsRamRoleCredentialProvider.java	65.11% <ø> (ø)
...redentials/provider/StaticCredentialsProvider.java	100.00% <ø> (ø)
...un/credentials/provider/URLCredentialProvider.java	40.22% <0.00%> (ø)
src/main/java/com/aliyun/credentials/Client.java	70.23% <66.66%> (ø)
...a/com/aliyun/credentials/EcsRamRoleCredential.java	100.00% <100.00%> (ø)
.../com/aliyun/credentials/OIDCRoleArnCredential.java	95.83% <100.00%> (ø)
...a/com/aliyun/credentials/RamRoleArnCredential.java	100.00% <100.00%> (ø)
...a/com/aliyun/credentials/RsaKeyPairCredential.java	100.00% <100.00%> (ø)
...ain/java/com/aliyun/credentials/URLCredential.java	95.83% <100.00%> (ø)
... and 9 more