build: allow sequential use of docker slim

.github/actions/docker-slim/action.yml

@@ -13,11 +13,13 @@ runs:
   steps:
     - name: Setup docker slim
       run: |
-        mkdir /tmp/ds
-        cd /tmp/ds
-        curl -L -o ds.tar.gz https://github.com/slimtoolkit/slim/releases/download/1.40.11/dist_linux.tar.gz
-        tar -xvf ds.tar.gz --strip-components 1
-        echo "/tmp/ds" >> $GITHUB_PATH
+        if [ -d "/tmp/ds" ]; then
+          mkdir /tmp/ds
+          cd /tmp/ds
+          curl -L -o ds.tar.gz https://github.com/slimtoolkit/slim/releases/download/1.40.11/dist_linux.tar.gz
+          tar -xvf ds.tar.gz --strip-components 1
+          echo "/tmp/ds" >> $GITHUB_PATH
+        fi
       shell: bash
     - name: Run docker slim
       run: slim build --target ${{ inputs.target }} --tag ${{ inputs.tag }} --preserve-path /usr/share/nginx/html