feat: Add new command option to set env file for pdm script

[Zheaoli]

Pull Request Checklist

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• Test cases added for changed code.

Describe what you have changed in this PR.

Fix #3355

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.24%. Comparing base (19f84aa) to head (cf0608f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3358      +/-   ##
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+ Coverage   85.21%   85.24%   +0.02%     
==========================================
  Files         112      112              
  Lines       11461    11472      +11     
  Branches     2505     2507       +2     
==========================================
+ Hits         9767     9779      +12     
+ Misses       1168     1167       -1     
  Partials      526      526              

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unittests	85.04% <100.00%> (+0.02%)	⬆️

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[frostming]

I would like to suggest some improvements

The env files can be cascaded in a way that more specific env file can override less specific ones. For example, if PDM_ENVIRONMENT=prod, we look for the following files and load them if exists:

1. .env (effective for all environments)
2. .env.prod (effective for prod only)
3. .env.local (effective for all environments)
4. .env.prod.local (effective for prod only)

The variables are merged in the above order, with the latter taking precedence.

The improvement is to make .local a special modifier rather than a regular environment name. It contains the env vars for the current machine only, and .env*.local should be added to the .gitignore, while other .env files can be shared safely.

Also happy to hear @noirbizarre 's thoughts since he is the one involved in PDM scripts the most.

[Zheaoli]

1. .env (effective for all environments)
2. .env.prod (effective for prod only)
3. .env.local (effective for all environments)
4. .env.prod.local (effective for prod only)

The variables are merged in the above order, with the latter taking precedence.

The improvement is to make .local a special modifier rather than a regular environment name. It contains the env vars for the current machine only, and .env*.local should be added to the .gitignore, while other .env files can be shared safely.

Nice idea! I will update it ASAP