Bump 2.x version to fix CMake compilation on /usr-merged distros

[kouta-kun]

Hi! Lately, I've been having issues building projects that use SDL_net on distros that have gone through the /usr merge (Debian, Arch Linux, probably some more). As I can see in the repository, this has already been fixed:

https://github.com/libsdl-org/SDL_net/blob/b29ffae31f1ea6b41cad5951f53c05a47f3dab06/sdl2_net-config.cmake.in#L11

But a new release + version bump has not been created since then, and some distros such as Arch Linux will not ship these kinds of changes as patches. Would it be possible to generate a 2.3.0 or 2.2.1 version bump so that this fix can be propagated into these distros?