Roll back to earler xeus-python version to fix runtime error on macOS

Windows and linux build are still broken, but recent updates broke Mac runtime, so until Windows is fixed, roll back to a previously working version on macOS:

    ERROR: during execute_request
    make_tuple(): unable to convert arguments to Python object (compile in debug mode for details)

Details:

Revert "ENH: Update xeus-python, xeus, and jedi libraries to get new features and fixes"
This reverts commit 47226c0.

Revert "Update xeus and nlohmann-json to fix Windows build error"
This reverts commit fb132d0.

Author: lassoan

SuperBuild/External_nlohmann_json.cmake

@@ -26,7 +26,7 @@ if(NOT DEFINED ${proj}_DIR AND NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
 
   ExternalProject_SetIfNotDefined(
     ${CMAKE_PROJECT_NAME}_${proj}_GIT_TAG
-    "v3.9.1"
+    "v3.6.1"
     QUIET
     )
 

SuperBuild/External_python-jedi.cmake

@@ -21,7 +21,7 @@ if(NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
 
   ExternalProject_SetIfNotDefined(
     ${CMAKE_PROJECT_NAME}_${proj}_VERSION
-    "0.15.2"
+    "0.17.0"
     QUIET
     )
 

SuperBuild/External_xeus-python.cmake

@@ -26,7 +26,7 @@ if(NOT DEFINED ${proj}_DIR AND NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
 
   ExternalProject_SetIfNotDefined(
     ${CMAKE_PROJECT_NAME}_${proj}_GIT_TAG
-    "0.8.3"
+    "4446eb49682e882cd77e7404a9c01f8c2d64f667"  # 0.7.1 + optional display and output redirections
     QUIET
     )
 

SuperBuild/External_xeus.cmake

@@ -26,7 +26,7 @@ if(NOT DEFINED ${proj}_DIR AND NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
 
   ExternalProject_SetIfNotDefined(
     ${CMAKE_PROJECT_NAME}_${proj}_GIT_TAG
-    "7062ef5e561098c0797a1534e89bbaef9563c03d"  # 0.24.1 + "not -> !" fix
+    "282844988a04739eb833423c59d37feb0518666b" # master
     QUIET
     )