Whitelist files not being parsed (#375)

It seems that there is a typo on the default rules.

config/default.go

@@ -138,5 +138,5 @@ title = "gitleaks config"
 
 [whitelist]
 	description = "Whitelisted files"
-	file = '''(^\.?gitleaks.toml$|(.*?)(jpg|gif|doc|pdf|bin)$)'''
+	files = [ '''(^\.?gitleaks.toml$|(.*?)(jpg|gif|doc|pdf|bin)$)''' ]
 `