Free up space on Ubuntu runner for nuttx spec tests.

LLVM 21 update uses more disk space and makes the standard runner fail
with "No space left on device".  Using the [free disk space
action](https://github.com/marketplace/actions/free-disk-space-ubuntu)
to delete the unused Android, Haskell, and .NET runtimes frees up space
on the runner.

Author: wffurr

.github/workflows/spec_test_on_nuttx.yml

@@ -37,6 +37,19 @@ jobs:
     permissions:
       contents: read
       actions: write
+    uses: jlumbroso/free-disk-space@v1.3.1
+    with:
+      # Deletes Android, Haskell, and .NET runtimes from the runner, freeing
+      # about 15 GB.  
+      android: true
+      dotnet: true
+      haskell: true
+      # Keeps the tool cache, some large packages, docker images, and swap.
+      # Some of these could also be removed if more space is needed.
+      tool-cache: false
+      large-packages: false
+      docker-images: false
+      swap-storage: false
     uses: ./.github/workflows/build_llvm_libraries.yml
     with:
       os: "ubuntu-22.04"