The squid package should not be present in the container or container image. Remove the squid package from Containerfile and rebuild the container image.
If there is no need to make the proxy server software available, removing it provides a safeguard against its activation.
The squid service can be disabled with the following command:
$ sudo systemctl mask --now squid.service
Running proxy server software provides a network-based avenue of attack, and should be removed if not needed.