Applied codestyle to all .cs files

src/NadekoBot/Common/RequireObjectPropertiesContractResolver.cs

@@ -1,4 +1,4 @@
-#nullable disable
+#nullable disable
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
 
@@ -12,4 +12,4 @@ public class RequireObjectPropertiesContractResolver : DefaultContractResolver
         contract.ItemRequired = Required.DisallowNull;
         return contract;
     }
-}
+}