Merge pull request #928 from pi-hole/fix/docker-namespace

* Use the namespace from secrets so others can build too.
* Add DOCKERHUB_NAMESPACE variable.
* Use hub namepace in all actions.

Signed-off-by: Dan Schaper <dan.schaper@pi-hole.net>

.github/workflows/nightly-build.yml

@@ -59,4 +59,4 @@ jobs:
               PIHOLE_VERSION=nightly
             push: true
             tags: |
-              pihole/pihole:nightly
+              ${{ secrets.DOCKERHUB_NAMESPACE }}/pihole:nightly

.github/workflows/test-and-build.yaml

@@ -38,7 +38,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v3
         with:
-          images: pihole/pihole
+          images: ${{ secrets.DOCKERHUB_NAMESPACE }}/pihole
           github-token: ${{ secrets.GITHUB_TOKEN }}
       -
         name: Set up QEMU

.github/workflows/workflow_dispatch.yml

@@ -64,4 +64,4 @@ jobs:
             PIHOLE_VERSION=${{ github.event.inputs.name }}
           push: true
           tags: |
-            pihole/pihole:${{ github.event.inputs.name }}
+            ${{ secrets.DOCKERHUB_NAMESPACE }}/pihole:${{ github.event.inputs.name }}