Prepare fails on Ubuntu 22.04

Building pygame_sdl2 now requires libsdl2-image 2.6.0 since this PR has been merged, but Ubuntu 22.04 is stuck on 2.0.x, so "prepare.sh" fails eventually:

Errors log

``` gen3/pygame_sdl2.image.c: In function ‘__pyx_pf_11pygame_sdl2_5image_init’: gen3/pygame_sdl2.image.c:1669:126: error: ‘IMG_INIT_JXL’ undeclared (first use in this function); did you mean ‘IMG_INIT_JPG’? 1669 | __pyx_v_11pygame_sdl2_5image_image_formats = IMG_Init((((((IMG_INIT_JPG | IMG_INIT_PNG) | IMG_INIT_TIF) | IMG_INIT_WEBP) | IMG_INIT_JXL) | IMG_INIT_AVIF)); | ^~~~~~~~~~~~ | IMG_INIT_JPG gen3/pygame_sdl2.image.c:1669:126: note: each undeclared identifier is reported only once for each function it appears in gen3/pygame_sdl2.image.c:1669:142: error: ‘IMG_INIT_AVIF’ undeclared (first use in this function); did you mean ‘IMG_INIT_TIF’? 1669 | __pyx_v_11pygame_sdl2_5image_image_formats = IMG_Init((((((IMG_INIT_JPG | IMG_INIT_PNG) | IMG_INIT_TIF) | IMG_INIT_WEBP) | IMG_INIT_JXL) | IMG_INIT_AVIF)); | ^~~~~~~~~~~~~ | IMG_INIT_TIF gen3/pygame_sdl2.image.c: In function ‘__pyx_pf_11pygame_sdl2_5image_6load’: gen3/pygame_sdl2.image.c:2520:27: warning: implicit declaration of function ‘IMG_LoadSizedSVG_RW’; did you mean ‘IMG_LoadSVG_RW’? [-Wimplicit-function-declaration] 2520 | __pyx_v_img = IMG_LoadSizedSVG_RW(__pyx_v_rwops, __pyx_v_width, __pyx_v_height); | ^~~~~~~~~~~~~~~~~~~ | IMG_LoadSVG_RW gen3/pygame_sdl2.image.c:2520:25: warning: assignment to ‘SDL_Surface *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion] 2520 | __pyx_v_img = IMG_LoadSizedSVG_RW(__pyx_v_rwops, __pyx_v_width, __pyx_v_height); | ^ gen3/pygame_sdl2.image.c: In function ‘__pyx_pymod_exec_image’: gen3/pygame_sdl2.image.c:4476:46: error: ‘IMG_INIT_JXL’ undeclared (first use in this function); did you mean ‘IMG_INIT_JPG’? 4476 | __pyx_t_2 = __Pyx_PyInt_From_IMG_InitFlags(IMG_INIT_JXL); if (unlikely(!__pyx_t_2)) __PYX_ERR(0, 48, __pyx_L1_error) | ^~~~~~~~~~~~ | IMG_INIT_JPG gen3/pygame_sdl2.image.c:4488:46: error: ‘IMG_INIT_AVIF’ undeclared (first use in this function); did you mean ‘IMG_INIT_TIF’? 4488 | __pyx_t_2 = __Pyx_PyInt_From_IMG_InitFlags(IMG_INIT_AVIF); if (unlikely(!__pyx_t_2)) __PYX_ERR(0, 49, __pyx_L1_error) | ^~~~~~~~~~~~~ | IMG_INIT_TIF error: command '/usr/bin/x86_64-linux-gnu-gcc' failed with exit code 1 ```

This is on latest Ubuntu 22.04 from a docker image:

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:        22.04
Codename:       jammy

It works using Ubuntu 22.10 (and maybe 23.04), but that means the build instructions are not valid anymore.

renpy / renpy-build

Prepare fails on Ubuntu 22.04 #58