Set minimum required xeus-lite version to 3.2.1 (#339)

* Set minimum required xeus-lite version to 3.2.1

* Apply PR suggestion

Author: mcbarton

CMakeLists.txt

@@ -91,6 +91,7 @@ endif()
 set(xeus_REQUIRED_VERSION 5.0.0)
 set(xeus_zmq_REQUIRED_VERSION 3.0.0)
 set(CppInterOp_REQUIRED_VERSION 1.7.0)
+set(xeus_lite_REQUIRED_VERSION 3.2.1)
 
 if (NOT TARGET xeus AND NOT TARGET xeus-static)
     find_package(xeus ${xeus_REQUIRED_VERSION} REQUIRED)
@@ -439,7 +440,7 @@ if(EMSCRIPTEN)
         message(FATAL_ERROR "Failed to run 'embuilder build sdl2'")
     endif()
     include(WasmBuildOptions)
-    find_package(xeus-lite REQUIRED)
+    find_package(xeus-lite ${xeus_lite_REQUIRED_VERSION} REQUIRED)
     add_executable(xcpp src/main_emscripten_kernel.cpp )
     target_link_libraries(xcpp PRIVATE xeus-lite)
     xeus_cpp_set_kernel_options(xcpp)