fix: update bennu for build changes

[GhostofGoes]

update bennu for build changes

Description

Update the bennu image to use Clifton's improvements (sandialabs/sceptre-bennu#44) to how the bennu packages are built.

This is WIP and not fully working. If building internally, add the srn script to -T in the Makefile.

Commits will be squashed before PR is marked as ready.

Related Issue

Related PR: sandialabs/sceptre-bennu#44

Type of Change

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• Bugfix
• New feature
• Documentation update
• Other (please describe):

Checklist

• This PR conforms to the process detailed in the Contributing Guide.
• I have included no proprietary/sensitive information in my code.
• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have tested my code.

Additional Notes

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