[fix]|installexternal.py] Fix import of urllib.request

This changed to be the required way of importing the lib in some newer Python versions.
https://docs.python.org/3.9/library/urllib.request.html and https://bugs.python.org/issue36701 
5 jobs for !2833 with fix/pythonscript-urllib-import
latest detached
Status Name Job ID Coverage
  Trigger
manual full-dune-2.7-clang
manual full-dune-2.7-gcc
manual full-dune-master-gcc
manual minimal-dune-2.7-gcc
 
  Downstream Modules
created trigger lecture