Move test_gdbm to use unittest.

Closes issue #1960. Thanks Giampaolo Rodola.
diff --git a/Misc/ACKS b/Misc/ACKS
index c2cad5c..cce6152 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -559,6 +559,7 @@
 Andy Robinson
 Jim Robinson
 Kevin Rodgers
+Giampaolo Rodola
 Mike Romberg
 Case Roole
 Timothy Roscoe