ci: use normal Docker builds for fork PRs instead of Depot (#22268)

Co-authored-by: Amp <amp@ampcode.com>

.github/workflows/docker-test.yml

@@ -15,7 +15,6 @@ on:
 
 jobs:
   build:
-    if: github.repository == 'paradigmxyz/reth'
     timeout-minutes: 45
     runs-on: ubuntu-latest
     permissions:
@@ -31,10 +30,22 @@ jobs:
           echo "sha=${{ github.sha }}" >> "$GITHUB_OUTPUT"
           echo "describe=$(git describe --always --tags)" >> "$GITHUB_OUTPUT"
 
+      - name: Detect fork
+        id: fork
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ] && [ "${{ github.event.pull_request.head.repo.full_name }}" != "${{ github.repository }}" ]; then
+            echo "is_fork=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "is_fork=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      # Depot build (upstream only)
       - name: Set up Depot CLI
+        if: steps.fork.outputs.is_fork == 'false'
         uses: depot/setup-action@v1
 
-      - name: Build reth image
+      - name: Build reth image (Depot)
+        if: steps.fork.outputs.is_fork == 'false'
         uses: depot/bake-action@v1
         env:
           DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
@@ -46,6 +57,24 @@ jobs:
           targets: ${{ inputs.hive_target }}
           push: false
 
+      # Docker build (forks)
+      - name: Set up Docker Buildx
+        if: steps.fork.outputs.is_fork == 'true'
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build reth image (Docker)
+        if: steps.fork.outputs.is_fork == 'true'
+        uses: docker/bake-action@v6
+        env:
+          VERGEN_GIT_SHA: ${{ steps.git.outputs.sha }}
+          VERGEN_GIT_DESCRIBE: ${{ steps.git.outputs.describe }}
+        with:
+          files: docker-bake.hcl
+          targets: ${{ inputs.hive_target }}
+          push: false
+          set: |
+            *.dockerfile=Dockerfile
+
       - name: Upload reth image
         uses: actions/upload-artifact@v6
         with: