Consistent Docker Buildx Action Version (#374)

Changed the Docker Buildx action version in the nethermind job to v4 to match the others AND Ensured consistent indentation for better readability.

These changes should improve the workflow's consistency and clarity

.github/workflows/pr.yml

@@ -31,6 +31,7 @@ jobs:
           file: geth/Dockerfile
           push: false
           platforms: ${{ matrix.arch }}
+
   reth:
     runs-on: ubuntu-latest
     strategy:
@@ -54,6 +55,7 @@ jobs:
           build-args: |
             FEATURES=${{ matrix.features }}
           platforms: ${{ matrix.arch }}
+
   nethermind:
     runs-on: ubuntu-latest
     strategy:
@@ -67,7 +69,7 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Build the Docker image
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v4
         with:
           context: .
           file: nethermind/Dockerfile