.github/workflows/build: enable pushing to dockerhub

Author: classabbyamp

.github/workflows/build.yaml

@@ -58,6 +58,7 @@ jobs:
         with:
           images: |
             ghcr.io/${{ github.repository_owner }}/void-${{ matrix.libc }}${{ matrix.variant }}
+            voidlinux/void-${{ matrix.libc }}${{ matrix.variant }}
           tags: |
             type=sha,prefix=
             type=raw,value=latest,enable={{is_default_branch}}
@@ -86,6 +87,13 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Login to DockerHub
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Build and push images
         id: build_and_push
         uses: docker/bake-action@v3