Use coverage flags to distinguish between runs

Author: urfeex

.github/workflows/ci.yml

@@ -58,6 +58,7 @@ jobs:
         with:
           fail_ci_if_error: true
           token: ${{ secrets.CODECOV_TOKEN }}
+          flags: ${{ matrix.env.ROBOT_MODEL }}-${{ matrix.env.URSIM_VERSION }}
       - name: Generate URSim log files
         if: always()
         run: |