fix(ci): pin the long-tail actions and retire scorecard-enforcer.yml

Closes the two residual `governance` failures left by the first sweep:

* `Workflow security linter` reported "Found unpinned actions" for actions
  outside the first pass's pin map (docker/*, slsa, julia-actions, softprops,
  ipdxco, codeql upload-sarif). Floating branch refs (@main / @master) are
  left alone on purpose — pinning those is a version decision.
* `Check Workflow Staleness` errors on `scorecard-enforcer.yml` by name (it
  is retired in favour of scorecard.yml -> standards scorecard-reusable.yml)
  and separately on Scorecard uploading SARIF to Code Scanning. Removing the
  retired file resolves both. It is removed only where scorecard.yml already
  exists, so Scorecard coverage is retained.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/generator-generic-ossf-slsa3-publish.yml

@@ -66,7 +66,7 @@ jobs:
       actions: read   # To read the workflow path.
       id-token: write # To sign the provenance.
       contents: write # To add assets to a release.
-    uses: slsa-framework/slsa-github-generator/.github/workflows/generator_generic_slsa3.yml@v2.1.0
+    uses: slsa-framework/slsa-github-generator/.github/workflows/generator_generic_slsa3.yml@f7dd8c54c2067bafc12ca7a55595d5ee9b75204a # v2.1.0
     with:
       base64-subjects: "${{ needs.build.outputs.digests }}"
       upload-assets: true # Optional: Upload to a new release