Upgrade SuperTuxKart to 1.3

[markmandel]

Is your feature request related to a problem? Please describe.

It would be nice to have the latest version of SuperTuxKart running in the example, rather than a hacked older version.

Describe the solution you'd like

Because of old limitations with the previous version of SuperTuxKart, we had to compile from source (it wouldn't allow AI connections not on localhost).

Since there is now a new version of SuperTuxKart that makes this a configurable option, we can upgrade (and new levels and stuff too), and instead download the binary and use that, rather than compile it from scratch.

We will need to ensure <ai-anywhere value="true" /> is in the configuration file (see link below for config file documentation), such that we can connect AI bots from outside the cluster/node (otherwise it only accepts connections from localhost).

It's possible that the main.go wrapper may need modification (since it makes the GameServer ready when it intercepts certain logs), but hopefully not.

Describe alternatives you've considered

N/A

Additional context

• https://github.com/googleforgames/agones/blob/main/examples/supertuxkart/Dockerfile
• https://github.com/supertuxkart/stk-code/blob/master/NETWORKING.md
• https://github.com/supertuxkart/stk-code/releases/tag/1.3