Add fetch-content to cmake config in CI

Add CMAKE_PROJECT_TOP_LEVEL_INCLUDES to the config step in CI.

Author: steve-downey

.github/workflows/ci.yml

@@ -93,7 +93,12 @@ jobs:
           echo ${{ matrix.config.cmake_args }}
           echo ${{ matrix.config.toolchain }}
           rm -rf .build
-          cmake ${{ matrix.config.cmake_args }} -DCMAKE_INSTALL_PREFIX=.install -DCMAKE_TOOLCHAIN_FILE="etc/${{ matrix.config.toolchain }}-toolchain.cmake" -B .build -S .
+          cmake ${{ matrix.config.cmake_args }} \
+            -DCMAKE_INSTALL_PREFIX=.install \
+            -DCMAKE_TOOLCHAIN_FILE="etc/${{ matrix.config.toolchain }}-toolchain.cmake" \
+            -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES="./cmake/use-fetch-content.cmake" \
+            -B .build \
+            -S .
       - name: CMake ASAN Build
         run: |
           set -x