bpo-39939: Add str.removeprefix and str.removesuffix (GH-18939)

Added str.removeprefix and str.removesuffix methods and corresponding
bytes, bytearray, and collections.UserString methods to remove affixes
from a string if present. See PEP 616 for a full description.
diff --git a/Misc/ACKS b/Misc/ACKS
index 8cb95dc..69865fe 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1660,6 +1660,7 @@
 Kalle Svensson
 Andrew Svetlov
 Paul Swartz
+Dennis Sweeney
 Al Sweigart
 Sviatoslav Sydorenko
 Thenault Sylvain