fix(ci): use /mnt for temporary files and dune cache

Should have more disk space.

Signed-off-by: Edwin Török <[email protected]>

.github/workflows/main.yml

@@ -122,6 +122,21 @@ jobs:
       - name: Update Ubuntu repositories
         run: sudo apt-get update
 
+      - name: Use disk with more space for $TMPDIR and $XDG_CACHE_HOME
+        run: |
+          df -h || true
+          sudo mkdir -p /mnt/build/tmp /mnt/build/cache
+          sudo chown $(id -u):$(id -g) /mnt/build
+        
+      - name: Use disk with more space for $TMPDIR
+        run: echo "TMPDIR=/mnt/build/tmp" >>"$GITHUB_ENV"
+
+      - name: Use disk with more space for $XDG_CACHE_HOME
+        run: echo "XDG_CACHE_HOME=/mnt/build/cache" >>"$GITHUB_ENV"
+
+      - name: Print opam environment
+        run: opam exec -- env
+
       - name: Use ocaml
         uses: ocaml/setup-ocaml@v2
         with: