Create ~/.pypirc securely (#13512).

There was a window between the write and the chmod where the user’s
password would be exposed, depending on default permissions.  Philip
Jenvey’s patch fixes it.
diff --git a/Misc/ACKS b/Misc/ACKS
index 9e662f6..0567069 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -512,6 +512,7 @@
 Drew Jenkins
 Flemming Kjær Jensen
 Philip H. Jensen
+Philip Jenvey
 MunSic Jeong
 Chris Jerdonek
 Pedro Diaz Jimenez