Fix build: remove gha cache (timeouts on runner), drop upstream check

.gitea/workflows/docker.yml

@@ -21,15 +21,6 @@ jobs:
           ref: ${{ github.sha }}
           fetch-depth: 0
 
-      - name: Check upstream for new opencode image
-        id: upstream
-        run: |
-          TOKEN=$(curl -s "https://ghcr.io/token?service=ghcr.io&scope=repository:anomalyco/opencode:pull" | jq -r .token)
-          DIGEST=$(curl -s -H "Authorization: Bearer $TOKEN" \
-            "https://ghcr.io/v2/anomalyco/opencode/manifests/latest" \
-            -H "Accept: application/vnd.oci.image.index.v1+json" 2>/dev/null | jq -r '.manifests[] | select(.platform.architecture=="amd64" and .platform.os=="linux") | .digest' || echo "")
-          echo "digest=${DIGEST}" >> "$GITHUB_OUTPUT"
-
       - name: Login to Gitea Package Registry
         uses: docker/login-action@v3
         with:
@@ -49,5 +40,7 @@ jobs:
           tags: |
             gitea.steffenillium.de/steffen/opencode-custom:latest
             gitea.steffenillium.de/steffen/opencode-custom:${{ github.sha }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
+
+      - name: Cleanup buildx
+        if: always()
+        run: docker buildx prune -af