remove outdated workaround

.github/workflows/build-checks.yml

@@ -87,13 +87,6 @@ jobs:
         working-directory: build
       - name: Set up problem matcher
         uses: ammaraskar/gcc-problem-matcher@0.3.0
-      # Work around https://github.com/actions/runner-images/issues/8659
-      - name: "Remove GCC 13 from runner image (workaround)"
-        shell: bash
-        run: |
-          sudo rm -f /etc/apt/sources.list.d/ubuntu-toolchain-r-ubuntu-test-jammy.list
-          sudo apt-get update
-          sudo apt-get install -y --allow-downgrades libc6=2.35* libc6-dev=2.35* libstdc++6=12.3.0-1ubuntu1~22.04 libgcc-s1=12.3.0-1ubuntu1~22.04
       - name: Build
         # Do not abort on errors and build/check the whole project
         run: cmake --build . -j $(nproc) -- --keep-going