Merge pull request #12664 from szarroug3/pathlib_demo

use pathlib.Path in demo.py

IPython/lib/demo.py

@@ -184,6 +184,7 b' import re'
 import shlex
 import sys
 import pygments
+from pathlib import Path
 
 from IPython.utils.text import marquee
 from IPython.utils import openpy
@@ -404,7 +405,7 b' class Demo(object):'
 
         filename = self.shell.mktempfile(self.src_blocks[index])
         self.shell.hooks.editor(filename,1)
-        with open(filename, 'r') as f:
+        with open(Path(filename), "r") as f:
             new_block = f.read()
         # update the source and colored block
         self.src_blocks[index] = new_block