Specify SDL version

[tophyr]

Pull Request Type

• GitHub Workflow changes
• Documentation or Wiki changes
• Build and Dependency changes
• Runtime changes
  • Render changes
  • Audio changes
  • Input changes
  • Network changes
  • Other changes

Description

Both vcpkg.json and the ever-in-progress Android version rely on specific versions of SDL, so we should specify the version in CMake too.

Checklist

• I have tested my changes locally and verified that they work as intended.
• I have documented any new or modified functionality.
• I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

[Lgt2x]

SDL 3.4 is out btw, may be worth updating

[tophyr]

i briefly looked at it but i'm still trying to catch up to SDL2 -> SDL3 architectural changes lol

[Lgt2x]

All good, I'll review #727