Fixes Centcom Ban DB erroring out with bad index (#3337)

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## About The Pull Request

BYOND 515 "fixes" an undocumented feature where vars can be accessed on
objects by accessing them like a list. I fix this on Yogstation too so I
might as well port it here cause you guys are nice (hi shiptest!)
yogstation13/Yogstation#22586

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## Why It's Good For The Game

We should be able to use this if we have it!

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## Changelog

:cl:
fix: Centcom Ban DB is now accessible again through PP
/:cl:

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code/modules/admin/topic.dm

@@ -1973,7 +1973,7 @@
 			if(response.body == "[]")
 				dat += "<center><b>0 bans detected for [ckey]</b></center>"
 			else
-				bans = json_decode(response["body"])
+				bans = json_decode(response.body)
 
 				//Ignore bans from non-whitelisted sources, if a whitelist exists
 				var/list/valid_sources