upgrade Soplex to 7.1.0, remove workaround for old code.

.github/workflows/ubuntu.yml

@@ -30,9 +30,9 @@ jobs:
       CPLEX_URL: ${{ secrets.CPLEX2211_LINUX_URL }}
       cplex_DIR: /home/runner/lib/ibm/ILOG/CPLEX_Studio2211/cplex
       CPLEX_LIB: /home/runner/lib/ibm/ILOG/CPLEX_Studio2211/cplex/bin/x86-64_linux/libcplex2211.so
-      soplex_DIR: /home/runner/lib/soplex-6.0.3x
-      SOPLEX_LIB: /home/runner/lib/soplex-6.0.3x/lib/
-      SOPLEX_INCLUDE: /home/runner/lib/soplex-6.0.3x/include/
+      soplex_DIR: /home/runner/lib/soplex-7.1.0
+      SOPLEX_LIB: /home/runner/lib/soplex-7.1.0/lib/
+      SOPLEX_INCLUDE: /home/runner/lib/soplex-7.1.0/include/
     steps:
       - name: Clone repository
         uses: actions/checkout@v3
@@ -56,14 +56,6 @@ jobs:
         run: |
           sudo apt-get -y install ${{ matrix.version.cxx }}
 
-      # TODO: Remove once issue with Ubuntu 22.04 and clang++-14 is resolved.
-      - name: Work around https://github.com/actions/runner-images/issues/8659
-        if: matrix.version.cxx == 'clang++-14'
-        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-* libgcc-s1=12.3.0-*
-
       # Only install CPLEX if its URL/secret is set.
       - name: Install CPLEX
         if: ${{ env.CPLEX_URL != 0 }}
@@ -79,7 +71,7 @@ jobs:
         run: |
           git clone https://github.com/scipopt/soplex.git
           cd soplex
-          git checkout a5df0814d67812c13a00f06eec507b4d071fb862
+          git checkout release-710
           cd ..
           cmake -S soplex -B build
           cmake --build build