Fix incorrect actions/checkout version comment in update-policies.yml

The pinned SHA (3d3c42e5...) resolves to actions/checkout v7.0.1, not
v4 as the comment claimed. This is the same class of mistake flagged
in PR #14685's review (actions/upload-artifact was pinned to a v4
comment but a v7.0.0 SHA) — verify comments against the actual tagged
version, not just assume the SHA matches its label.

Author: ggbecker

.github/workflows/update-policies.yml

@@ -56,7 +56,7 @@ jobs:
             python3-setuptools
 
       - name: Checkout ComplianceAsCode/content
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v4
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           path: content