Currently, environment files are copied to container image during build.
Environment files contains secrets and should not be in container images.
Per [discussion 4474](https://github.com/cookiecutter/cookiecutter-django/discussions/4474), this is likely a bug.
This change excludes all environment files from being copied to container image.
Co-authored-by: Bruno Alla <browniebroke@users.noreply.github.com>