Fix CFLAGS on default behavior for later setuptools versions

Author: rhpvorderman

.github/workflows/ci.yml

@@ -243,14 +243,14 @@ jobs:
           CIBW_ENVIRONMENT_LINUX: >-
             PYTHON_ISAL_BUILD_CACHE=True
             PYTHON_ISAL_BUILD_CACHE_FILE=/tmp/build_cache
-            CFLAGS="-g0 -DNDEBUG"
+            CFLAGS="-O3 -DNDEBUG"
           CIBW_ENVIRONMENT_WINDOWS: >-
             PYTHON_ISAL_BUILD_CACHE=True
             PYTHON_ISAL_BUILD_CACHE_FILE=${{ runner.temp }}\build_cache
           CIBW_ENVIRONMENT_MACOS: >-
             PYTHON_ISAL_BUILD_CACHE=True
             PYTHON_ISAL_BUILD_CACHE_FILE=${{ runner.temp }}/build_cache
-            CFLAGS="-g0 -DNDEBUG"
+            CFLAGS="-O3 -DNDEBUG"
       - name: Build sdist
         if: ${{runner.os == 'Linux' && matrix.cibw_archs_linux == 'x86_64'}}
         run: |