SDL2: updated to 2.30.3

2.30.3

This is a stable bugfix release, with the following changes:

Fixed Win+V handling (pasting from clipboard history) on Windows
Fixed Caps Lock and Backspace key mapping for the Colemak keyboard layout on Windows
Fixed mouse warp on XWayland
Reduced startup time when scanning for game controllers on Linux
Fixed building with C89 compilers
Fixed building with the GDK SDK on Windows

(adam)