Update actions/checkout action to v7

Author: renovate[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
       contents: write
     steps:
       - name: "📥 Checkout Code (Full History)"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           fetch-depth: 0
 
@@ -45,7 +45,7 @@ jobs:
       contents: read
     steps:
       - name: "📥 Checkout Code"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: "📦 Setup Buf"
         uses: bufbuild/buf-setup-action@v1.50.0
@@ -78,7 +78,7 @@ jobs:
       id-token: write
     steps:
       - name: "📥 Checkout Code (Full History)"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           fetch-depth: 0