Ensure we install libstdc++6

Author: MilesCranmer

.github/workflows/main.yml

@@ -69,6 +69,9 @@ jobs:
         with:
           version: ${{ matrix.julia-version }}
           arch: ${{ matrix.architecture }}
+      - name: Ensure libstdc++ installed
+        run: sudo apt-get install libstdc++6
+        if: matrix.os == 'ubuntu-latest'
       - run: python src/julia/find_libpython.py --list-all --verbose
       - name: Install tox
         run: |