try to fix ganymede build

.gitea/workflows/build-nginx.yaml

@@ -9,6 +9,14 @@ jobs:
   "Build nginx docker images":
     runs-on: woryzen
     steps:
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3.4.0
+        with:
+          driver: docker-container
+          platforms: |
+            linux/amd64
+            linux/arm64
       -
         name: Login to Gitea container registry
         uses: docker/login-action@v3
@@ -20,7 +28,6 @@ jobs:
         name: Build and push nginx vanilla images
         uses: docker/build-push-action@v6
         with:
-          builder: multiplatform-builder
           context: "{{defaultContext}}:nginx"
           platforms: |
             linux/amd64
@@ -43,7 +50,6 @@ jobs:
         name: Build and push nginx custom images
         uses: docker/build-push-action@v6
         with:
-          builder: multiplatform-builder
           context: "{{defaultContext}}:nginx"
           platforms: |
             linux/amd64

jupyter-ganymede/Dockerfile

@@ -4,12 +4,7 @@ RUN --mount=type=cache,target=/var/cache/apk/,sharing=locked \
     apk add python3 python3-dev pipx gcc g++ musl-dev linux-headers which curl libffi-dev git
 RUN adduser jovyan -u 1000 --system -s /bin/sh -h /home/jovyan
 
-FROM --platform=$BUILDPLATFORM alpine:3.22 AS java-build
-RUN --mount=type=cache,target=/var/cache/apk/,sharing=locked \
-    apk update &&\
-    apk add python3 python3-dev pipx gcc g++ musl-dev linux-headers which curl libffi-dev git
-RUN adduser jovyan -u 1000 --system -s /bin/sh -h /home/jovyan
-
+FROM --platform=$BUILDPLATFORM build-base AS java-build
 RUN --mount=type=cache,target=/var/cache/apk/,sharing=locked \
     apk add openjdk11-jdk maven
 USER jovyan