ci: test github actions

.github/workflows/sub_test.yaml

@@ -41,6 +41,22 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
+      -
+        name: Free Disk Space (Ubuntu)
+        uses: jlumbroso/free-disk-space@main
+        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 necessary for your workflow
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: true
       -
         name: Checkout
         uses: actions/checkout@v4