Update actions/checkout digest to df4cb1c (#7)

Author: renovate[bot]

.github/workflows/manual-build.yml

@@ -27,7 +27,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           fetch-depth: 0
           persist-credentials: false

.github/workflows/sync.yml

@@ -20,7 +20,7 @@ jobs:
       contents: write
       issues: write
     steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           fetch-depth: 0
           persist-credentials: true # needed for git push later

.github/workflows/zizmor.yml

@@ -16,7 +16,7 @@ jobs:
       security-events: write
 
     steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           persist-credentials: false