Update shumlib to use the head of the upstream.

[Whyborn]

Move to the head of shumlib upstream, in preparation for merging in the extrapolation fix identified here (thanks @paocorrales). We want to be up to date with the upstream before we apply the fix, and attempt to merge the fix into said upstream.

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🚀 The latest prerelease access-am3/pr45-3 at db40ac7 is here: #45 (comment) 🚀

[github-actions]

🚀 Attempted to deploy access-am3 Prerelease pr45-1 with commit 4bfaae1

🖥️ Gadi Deployment ❌

[github-actions]

🚀 Attempted to deploy access-am3 Prerelease pr45-2 with commit b27dffb

🖥️ Gadi Deployment ❌

[github-actions]

🚀 Attempted to deploy access-am3 Prerelease pr45-3 with commit db40ac7

🖥️ Gadi Deployment ✔️

Usage Instructions

access-am3, defined in spack.yaml, will be deployed to Gadi as:

• 2026.06.000 as a Release (when merged).
• pr45-3 as a Prerelease (during this PR).

This Prerelease is accessible on Gadi using:

module use /g/data/vk83/prerelease/modules
module load access-am3/pr45-3

When using the above modules, the binaries shall be on your $PATH.

For advanced users, this Prerelease is also accessible on Gadi via /g/data/vk83/prerelease/apps/spack/1.1/spack in the access-am3-pr45-3 environment.
Due to inode-saving measures, one will have to manually untar the environment metadata before environment activation with tar -xf .spack-env .spack-env.tar. It will require one to have write privileges.

Configuration Information

This Prerelease is deployed using:

• access-nri/spack on branch 1.1
• ACCESS-NRI/upstream-spack-packages version access/v1.1
• access-nri/access-spack-packages version 2026.05.005
• access-nri/spack-config version 2026.05.004

If the above was not what was expected, commit changes to config/versions.json in this PR, or propose changes to build-cds config/settings.json.