change link of clad to ssh instead of https

Author: ChuanqiXu9

interpreter/cling/tools/plugins/clad/CMakeLists.txt

@@ -73,7 +73,7 @@ list(APPEND _clad_cmake_logging_settings LOG_OUTPUT_ON_FAILURE ON)
 
 ExternalProject_Add(
   clad
-  GIT_REPOSITORY https://github.com/vgvassilev/clad.git
+  GIT_REPOSITORY git@github.com:vgvassilev/clad.git
   GIT_TAG v1.2
   UPDATE_COMMAND ""
   PATCH_COMMAND ${_clad_patch_command}