Revert "switch examples_ntt_kyber_dilithium_neon_core to run on MacOS"

This reverts commit d19efbe.

.github/workflows/test_basic.yaml

@@ -82,12 +82,9 @@ jobs:
             github.event.pull_request.user.login == 'dop-amin' ||
             github.event.pull_request.user.login == 'mkannwischer'
             }}
-    runs-on: macos-latest
+    runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: actions/setup-python@v5
-      with:
-        python-version: '3.12' 
     - name: Install python dependencies
       run: |
         python3 -m venv venv