Add image pulling for nullify dast

Description

The nullify image is pulled from the ghcr in dast-local

[ ] I have added one of the patch, minor, major or no-release labels
[ ] I have linked an issue from this repository using the Development option
[ ] I have performed a self-review of my own code
[ ] I have checked for redundant or commented out code
[ ] I have commented my code where I can't make it self-documenting
[ ] I have made corresponding changes to the documentation
[ ] I have added any appropriate tests