Update simulator link to point to sr2023.4

Author: Adimote

simulator/index.md

@@ -35,7 +35,7 @@ local development you will need to install these yourself.
 ### Installing the simulation
 
 1. Create a directory, perhaps called `simulation` where you will store your robot code.
-2. [Download the simulation](https://github.com/srobo/competition-simulator/releases/download/sr2023.3/competition-simulator-sr2023.3.zip)
+2. [Download the simulation](https://github.com/srobo/competition-simulator/releases/download/sr2023.4/competition-simulator-sr2023.4.zip)
   and unzip it as a subdirectory of that directory:
   ```
   simulation