bpo-32885: Tools/scripts/pathfix.py: Add -n option for no backup~ (#5772)

Creating backup files with ~ suffix can be undesirable in some environment,
such as when building RPM packages. Instead of requiring the user to remove
those files manually, option -n was added, that simply disables this feature.

-n was selected because 2to3 has the same option with this behavior.
diff --git a/Misc/ACKS b/Misc/ACKS
index d8179c8..d752d8a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -687,6 +687,7 @@
 Brad Howes
 Mike Hoy
 Ben Hoyt
+Miro Hrončok
 Chiu-Hsiang Hsu
 Chih-Hao Huang
 Christian Hudon