Update actions/checkout action to v7

Author: renovate[bot]

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           fetch-depth: 2
 
@@ -46,7 +46,7 @@ jobs:
     if: github.event_name == 'push' && github.ref_name == 'main'
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Generate image tag
         id: image

.github/workflows/mirror.yml

@@ -9,7 +9,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
       with:
         fetch-depth: 0
     - name: Mirror + trigger CI