dist CI: Disable user_group variation

It seems not supported in newer ubuntu 24.04 images.

.github/workflows/dist.yml

@@ -38,7 +38,7 @@ jobs:
       - name: dependencies
         run: sudo apt-get update && sudo apt-get install ${{ env.deps }} reprotest ${{ matrix.archdeps }}
       - name: run
-        run: reprotest 'CFLAGS="${{ matrix.archconfigflags }}" CXXFLAGS="${{ matrix.archconfigflags }}" rm -rf build && cmake -Bbuild -DUSE_ASYNC:BOOL=OFF && cmake --build build && ctest --test-dir build -T test -j1 --output-on-failure && touch success' success
+        run: reprotest --vary=-user_group 'CFLAGS="${{ matrix.archconfigflags }}" CXXFLAGS="${{ matrix.archconfigflags }}" rm -rf build && cmake -Bbuild -DUSE_ASYNC:BOOL=OFF && cmake --build build && ctest --test-dir build -T test -j1 --output-on-failure && touch success' success
 
   distcheck: