install nlohmann_json in the container

Author: frs69wq

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Install prereqs
         run: |
           sudo apt-get update
-          sudo apt-get install -y libgraphviz-dev libboost-all-dev
+          sudo apt-get install -y libgraphviz-dev libboost-all-dev nlohmann-json3-dev
 
       - name: Install SimGrid
         run: |