Update actions/upload-artifact to v4

and remove hardcoded alpine runner

.forgejo/workflows/main.yml

@@ -10,13 +10,7 @@ on:
 jobs:
   cache:
     runs-on: docker
-    container:
-      image: 'alpine:latest'
     steps:
-      - name: Install curl
-        run: |
-          apk add --no-cache curl
-
       - name: Download OSM data
         run: |
           curl -L -o osm.pbf \
@@ -37,9 +31,10 @@ jobs:
           output_file: competences-territoriales.geojson
 
       - name: Upload as artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: competences-territoriales
+          path: competences-territoriales.geojson
 
       - name: Upload to Forgejo Package Registry
         run: |