Skip docker compose images with env param

[robaiken]

What are you trying to accomplish?

Add support for environment variable handling in Docker Compose file parsing. Currently, when Docker Compose files contain environment variables in version/tag specifications (e.g., image: ${DOCKER_IMAGE}), the parser attempts to process these as concrete versions, leading to incorrect dependency tracking.

This change ensures that dependencies with environment variable tags are skipped during parsing, while still properly handling dependencies with concrete version tags. This is important because we cannot meaningfully track or update dependencies where the version is determined at runtime through environment variables.

Thanks to @gmile #390 (comment) for reporting this issue

Anything you want to highlight for special attention from reviewers?

Adding a simple environment variable check in version_from rather than modifying the core parsing logic

How will you know you've accomplished your goal?

Dependencies with environment variable tags are properly skipped

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.