bpo-40394 - difflib.SequenceMatched.find_longest_match default args (GH-19742)

* bpo-40394 - difflib.SequenceMatched.find_longest_match default args

Added default args to find_longest_match, as well as related tests.
diff --git a/Misc/ACKS b/Misc/ACKS
index 89f37e5..21822dd 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -88,6 +88,7 @@
 Stig Bakken
 Aleksandr Balezin
 Greg Ball
+Lewis Ball
 Luigi Ballabio
 Thomas Ballinger
 Jeff Balogh