set C++ 17 and add fmtlib to test container

cmake/AddRoot.cmake

@@ -20,6 +20,6 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
   message(STATUS "Attach -fconcepts to the compiler flags to silence warnings.")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fconcepts")
 endif()
-# require the C++ standard 20 and don't want to fall back to lower
+# require the C++ standard 17 and don't want to fall back to lower
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 17)

docker/Dockerfile

@@ -3,7 +3,7 @@ FROM rootproject/root:6.30.04-ubuntu22.04
 
 # Install necessary packages
 RUN apt-get update -y
-RUN apt-get install -y ca-certificates gpg wget git make python3-pip openmpi-bin libopenmpi-dev libboost-all-dev openssh-client nlohmann-json3-dev
+RUN apt-get install -y ca-certificates gpg wget git make python3-pip libfmt-dev  openmpi-bin libopenmpi-dev libboost-all-dev openssh-client nlohmann-json3-dev
 
 RUN python3 -m pip install GitPython && python3 -m pip install git+https://github.com/cms-nanoAOD/correctionlib.git
 
@@ -20,4 +20,4 @@ RUN cd onnxruntime && ./build.sh --config Release --update --build --build_share
 # Install tini
 RUN apt-get install -y tini
 
-ENTRYPOINT ["/usr/bin/tini", "--"]
+ENTRYPOINT ["/usr/bin/tini", "--"]