ci/cd: migrate github actions to depot builds and runners

.github/workflows/build-next.yml

@@ -9,17 +9,18 @@ concurrency:
   group: build-next-image
   cancel-in-progress: true
 
+permissions:
+  contents: read
+  packages: write
+  id-token: write
+  attestations: write
+
 jobs:
   build-next:
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      packages: write
-      id-token: write
-      attestations: write
+    runs-on: depot-ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -34,6 +35,9 @@ jobs:
         with:
           go-version-file: "backend/go.mod"
 
+      - name: Set up Depot CLI
+        uses: depot/setup-action@v1
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3