Add back removed other repo owners in GH docker actions

In cf96ab45c198fbdc, support was added for using Docker related Github
actions in repositories of other owners. This was pretty helpful as it
allowed running modified forks off of main in a nightly fashion before
patches were pushed upstream. This was 6e870cdccc9ac845b678b, add it
back

.github/workflows/docker.yml

@@ -24,9 +24,9 @@ jobs:
         uses: docker/metadata-action@v5
         with:
           images: |
-            docker.io/miniflux/miniflux
-            ghcr.io/miniflux/miniflux
-            quay.io/miniflux/miniflux
+            docker.io/${{ github.repository_owner }}/miniflux
+            ghcr.io/${{ github.repository_owner }}/miniflux
+            quay.io/${{ github.repository_owner }}/miniflux
           tags: |
             type=ref,event=pr
             type=schedule,pattern=nightly
@@ -37,9 +37,9 @@ jobs:
         uses: docker/metadata-action@v5
         with:
           images: |
-            docker.io/miniflux/miniflux
-            ghcr.io/miniflux/miniflux
-            quay.io/miniflux/miniflux
+            docker.io/${{ github.repository_owner }}/miniflux
+            ghcr.io/${{ github.repository_owner }}/miniflux
+            quay.io/${{ github.repository_owner }}/miniflux
           tags: |
             type=ref,event=pr,suffix=-distroless
             type=schedule,pattern=nightly,suffix=-distroless