Update BaseConfig.php

[zl59503020]

Exclude when the configuration class attribute is $path, getenv will get the value of system path when env is not configured

Description
Under windows, if the env value is not configured, the value of (new \Config\Cookie())->path will be wrong
same question #853
https://www.php.net/manual/zh/function.getenv.php#122599

Checklist:

• Securely signed commits
• Component(s) with PHPdocs
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

---------Remove from here down in your description----------

Notes

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• If the PR solves an issue, reference it with a suitable verb and the issue number
  (e.g. fixes 12345)
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  to the develop branch of the project repository