Restore dockerhub login option

Author: thespad

.github/workflows/build-split-image.yml

@@ -159,6 +159,13 @@ jobs:
     outputs:
       final-image: ${{ steps.image_tags.outputs.final_image }}
     steps:
+      -
+        name: Login to DockerHub
+        if: matrix.registry == 'docker.io'
+        uses: docker/login-action@v3.6.0
+        with:
+          username: ${{ inputs.dockerhub_user }}
+          password: ${{ secrets.dockerhub_password }}
       -
         name: Login to GitHub Container Registry
         if: matrix.registry == 'ghcr.io'