Update actions/checkout digest to b4ffde6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
       - name: Set up Python
         uses: actions/setup-python@v4
         with:

.github/workflows/container_build.yml

@@ -28,7 +28,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
 
       - name: Log in to the Container registry
         uses: docker/login-action@v3