chore(ci): bump actions off deprecated Node 20 (#2)

actions/checkout@v4 -> @v6, actions/setup-go@v5 -> @v6,
peter-evans/create-pull-request@v7 -> @v8. Pinned major
versions; all three were flagged by the runner deprecation
notice (Node 20 forced off June 2 2026, removed Sept 16 2026).

.github/workflows/regen.yml

@@ -13,12 +13,12 @@ jobs:
   regen:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0   # full history so audit -drift can compare against main
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: '1.25.x'
           check-latest: true
@@ -89,7 +89,7 @@ jobs:
 
       - name: Open PR
         if: steps.diff.outputs.no_changes != 'true'
-        uses: peter-evans/create-pull-request@v7
+        uses: peter-evans/create-pull-request@v8
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           commit-message: |