install gcc-11 where necessary in ci

Author: oscarhiggott

.github/workflows/ci.yml

@@ -156,6 +156,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: true
+      - name: Install g++-11 (Ubuntu)
+        if: matrix.os == 'ubuntu-latest'
+        run: |
+          sudo apt-get update -y -qq
+          sudo apt-get install -y -qq gcc-11 g++-11
       - run: CC=gcc-11 CXX=g++-11 cmake .
         if: matrix.os == 'ubuntu-latest'
       - run: cmake .
@@ -172,6 +177,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: true
+      - name: Install g++-11 (Ubuntu)
+        if: matrix.os == 'ubuntu-latest'
+        run: |
+          sudo apt-get update -y -qq
+          sudo apt-get install -y -qq gcc-11 g++-11
       - run: CC=gcc-11 CXX=g++-11 cmake .
         if: matrix.os == 'ubuntu-latest'
       - run: cmake .