Fix image-build: install docker-cli on runner host

.forgejo/workflows/image-build.yaml

@@ -10,6 +10,7 @@ on:
 env:
   REGISTRY: forgejo.coulomb.social
   IMAGE_NAME: coulomb/forgejo-actions-probe
+  DOCKER_HOST: tcp://127.0.0.1:2375
 
 jobs:
   image-build:
@@ -18,12 +19,16 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Install docker CLI
+        run: |
+          set -eu
+          apk add --no-cache docker-cli
+          docker version
+
       - name: Login to Forgejo registry
-        uses: docker/login-action@v3
-        with:
-          registry: ${{ env.REGISTRY }}
-          username: ${{ secrets.REGISTRY_USER }}
-          password: ${{ secrets.REGISTRY_TOKEN }}
+        run: |
+          set -eu
+          echo "${{ secrets.REGISTRY_TOKEN }}" | docker login "${REGISTRY}"             -u "${{ secrets.REGISTRY_USER }}" --password-stdin
 
       - name: Build and push
         run: |