Update dependabot to also update GH-A workflows

[abejgonzalez]

See title. Updates CI dependencies if necessary.

Related PRs / Issues:

Type of change:

• Bug fix
• New feature
• Other enhancement

Impact:

• RTL change
• Software change (RISC-V software)
• Build system change
• Other

Contributor Checklist:

• Did you set main as the base branch?
• Is this PR's title suitable for inclusion in the changelog and have you added a changelog:<topic> label?
• Did you state the type-of-change/impact?
• Did you delete any extraneous prints/debugging code?
• Did you mark the PR with a changelog: label?
• (If applicable) Did you update the conda .conda-lock.yml file if you updated the conda requirements file?
• (If applicable) Did you add documentation for the feature?
• (If applicable) Did you add a test demonstrating the PR?

• (If applicable) Did you mark the PR as Please Backport?

[abejgonzalez]

Ugh. We need to duplicate repository/organization secrets into dependabot secrets for PRs to auto-open and use said secrets. Doing this now.

[abejgonzalez]

Ugh. We need to duplicate repository/organization secrets into dependabot secrets for PRs to auto-open and use said secrets. Doing this now.

Actually, I've just removed the offending secret (BUILDDIR) that is used in the "full flow" CI. This just stores the temporary Chipyard directory in the /tmp/ area (assuming that directory doesn't get cleaned up while CI is running - which should be rare if anything).