fix: Add disk cleanup step to test_dockerfile CI job

The recent dependency updates (torch 2.7.1 → 2.9.0, transformers 4.52.4 → 4.57.1,
etc.) increased the Docker image build size, causing the test_dockerfile job to fail
with "No space left on device" errors.

This adds the same disk cleanup step that's already used in the docker-publish workflow,
freeing up ~17GB by removing dotnet, ghc, and boost which aren't needed for our builds.

Resolves the "ERROR: Could not install packages due to an OSError: [Errno 28] No space
left on device" error in CI.

Author: luke-kucing

.github/workflows/ci.yml

@@ -118,6 +118,10 @@ jobs:
       uses: actions/setup-python@v6
       with:
         python-version: ${{ env.PYTHON_VERSION }}
+    - name: Free up disk space
+      run: |
+        # Clear some space (https://github.com/actions/runner-images/issues/2840)
+        sudo rm -rf /usr/share/dotnet /opt/ghc /usr/local/share/boost
     - name: Test Dockerfile
       run: |
         python${{ env.PYTHON_VERSION }} -m venv .venv