ci: try freeing some disk space for gui tests

Author: syphar

.github/workflows/ci.yml

@@ -71,6 +71,22 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
+      - name: Free Disk Space (Ubuntu)
+        uses: jlumbroso/free-disk-space@v1.3.1
+        with:
+          # this might remove tools that are actually needed,
+          # if set to "true" but frees about 6 GB
+          tool-cache: false
+
+          # all of these default to true, but feel free to set to
+          # "false" if our workflow needs parts
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: true
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3