Disable warning in C++20 mode

Author: joto

.github/workflows/ci.yml

@@ -66,6 +66,7 @@ jobs:
           - image: "debian:experimental"
             c_compiler: clang
             cpp_compiler: clang++
+            CXXFLAGS: -Wno-variadic-macro-arguments-omitted
     container:
       image: ${{ matrix.image }}
       env:
@@ -173,4 +174,3 @@ jobs:
       - uses: ./.github/actions/cmake-windows
       - uses: ./.github/actions/build-windows
       - uses: ./.github/actions/ctest-windows
-