Add a cmake formatting tool in the CI

.github/workflows/tests.yml

@@ -26,6 +26,20 @@ jobs:
       if: always()
       uses: fsfe/reuse-action@v4
 
+  cmake-format:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install gersemi
+        run: |
+          apt-get --yes update &&apt-get --yes install python3-pip python3-venv
+          python3 -m venv ./gersemi
+          . ./gersemi/bin/activate
+          python3 -m pip install gersemi
+      - name: Run gersemi
+        run:
+          gersemi --line-length 100 --indent 4 --check cmake/DDCVendorConfiguration.cmake
+          find CMakeLists.txt tests/ examples/ benchmarks/ -name 'CMakeLists.txt' -exec gersemi --definitions $PWD/cmake --line-length 100 --indent 4 --check '{}' '+'
+
   id_repo:
     runs-on: ubuntu-latest
     steps: