fix: reduce weekly security scan build time (amd64 only, 60min timeout)

.github/workflows/security-weekly-rebuild.yml

@@ -19,7 +19,7 @@ jobs:
   security-rebuild:
     name: Security Rebuild & Scan
     runs-on: ubuntu-latest
-    timeout-minutes: 45
+    timeout-minutes: 60
     permissions:
       contents: read
       packages: write
@@ -66,7 +66,7 @@ jobs:
         uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6
         with:
           context: .
-          platforms: linux/amd64,linux/arm64
+          platforms: linux/amd64
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}