Fix CI issue

Author: lemire

.github/workflows/ubuntu20-cxx20.yml

@@ -13,7 +13,7 @@ jobs:
         run: |
           mkdir build &&
           cd build &&
-          cmake -DCMAKE_CXX_STANDARD=20 -DFASTFLOAT_CONSTEXPR_TESTS=ON -DFASTFLOAT_TEST=ON -DCMAKE_INSTALL_PREFIX:PATH=destination ..  &&
+          cmake -DCMAKE_CXX_STANDARD=20 -DFASTFLOAT_TEST=ON -DCMAKE_INSTALL_PREFIX:PATH=destination ..  &&
           cmake --build .   &&
           ctest --output-on-failure  &&
           cmake --install .