Update actions/checkout digest to b4ffde6

Author: renovate[bot]

.github/workflows/auto-merge.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633 # v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
 
       - name: Create app token
         id: create-app-token

.github/workflows/pull-request.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633 # v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
 
       - name: Setup buildx
         uses: docker/setup-buildx-action@0d103c3126aa41d772a8362f6aa67afac040f80c # v3