Fix chat size cvar float parse (#14468)

* Fix chat size float parse

* Use dot separator

* Return comma value separator

Content.Client/UserInterface/Systems/Chat/ChatUIController.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Linq;
 using Content.Client.Administration.Managers;
 using Content.Client.Chat;
@@ -236,8 +237,8 @@ public sealed class ChatUIController : UIController
         var split = sizing.Split(",");
 
         var chatSize = new Vector2(
-            float.Parse(split[0]),
-            float.Parse(split[1]));
+            float.Parse(split[0], CultureInfo.InvariantCulture),
+            float.Parse(split[1], CultureInfo.InvariantCulture));
 
 
         screen.SetChatSize(chatSize);