The expand logic for env tag options has been modified, and the customOptions function has been refactored

[astak16]

1. If the environment variable key specified in env does not exist in the environment variables, and the key specified in envDefault is in the format of "${var}" or "$var", after being read, it is not replaced with the desired value.
2. the merging of customOptions and options has been written as the mergeOptions function.

I’m not sure if you accept these two commits.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (52e7186) to head (8f2e342).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #349   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          625       618    -7     
=========================================
- Hits           625       618    -7     

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[astak16]

Sorry, the two "fix: typo" commits were because I forgot to run the test cases.

[caarlos0]

thank you!