blacklist myself from mention-bot; it is annoying (#373)

diff --git a/.mention-bot b/.mention-bot
index 13b85d6..55ccb51 100644
--- a/.mention-bot
+++ b/.mention-bot
@@ -7,6 +7,6 @@
     "Misc/NEWS"
   ],
   "userBlacklist": [],
-  "userBlacklistForPR": [],
+  "userBlacklistForPR": ["benjaminp"],
   "requiredOrgs": ["python"]
 }