wpstarter: v3 Not Compatible with Pantheon or read-only root file systems

Describe the bug

The new .env handling appears to be attempting to write out a cached PHP file. This is not compatible with read-only file systems or containers, hosting such as Pantheon has a read-only code file system.

To Reproduce

Steps to reproduce the behavior:

1. Set the site root with no write permissions, or setup a site on Pantheon.
2. See errors in the logs about trying to write .env.cached.php

file_put_contents(/code/.env.cached.php): Failed to open stream: Permission deniedweb/wp-content/vendor/wecodemore/wpstarter/src/Env/WordPressEnvBridge.php:567

Expected behavior

The use of the .env setup shouldn’t be attempting to write a temporary file in the root of the file system, worst case it should be writing to TEMP space.