Add cache dependency path to setup-go step

[dms1981]

A reference to the issue / Description of it

Removes the cache dependency failed message seen in Terraform jobs for core-* environments.

How does this PR fix the problem?

Hardcodes the relevant go.sum location.
See here for more detail on this flag.

How has this been tested?

Tested in this action manual run: https://github.com/ministryofjustice/modernisation-platform/actions/runs/9399380420

Deployment Plan / Instructions

Will this deployment impact the platform and / or services on it?

{Please write here}

Checklist (check x in [ ] of list items)

• I have performed a self-review of my own code
• All checks have passed
• I have made corresponding changes to the documentation
• Plan and discussed how it should be deployed to PROD (If needed)

Additional comments (if any)

{Please write here}

[github-actions]

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</details> #### `Checkov Scan` Success
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CTFLint Scan Success

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Setting default tflint config...
Running tflint --init...
Installing "terraform" plugin...
Installed "terraform" (source: github.com/terraform-linters/tflint-ruleset-terraform, version: 0.5.0)
tflint will check the following folders:

Trivy Scan Success

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Trivy will check the following folders: