Please make opencv-python-headless support FFmpeg 9.0

Errors:

[ 80%] Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_ffmpeg.cpp.o
In file included from /wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg.cpp:50:
In file included from /wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:175:
/wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg_hw.hpp:760:82: error: no member named 'pix_fmts' in 'AVCodec'
  760 |             if (av_codec_is_encoder(c) && hw_native_fmt != AV_PIX_FMT_NONE && c->pix_fmts) {
      |                                                                               ~  ^
/wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg_hw.hpp:761:36: error: no member named 'pix_fmts' in 'AVCodec'
  761 |                 for (int i = 0; c->pix_fmts[i] != AV_PIX_FMT_NONE; i++) {
      |                                 ~  ^
/wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg_hw.hpp:762:28: error: no member named 'pix_fmts' in 'AVCodec'
  762 |                     if (c->pix_fmts[i] == hw_native_fmt) {
      |                         ~  ^
In file included from /wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg.cpp:50:
/wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:2586:24: error: no member named 'supported_framerates' in 'AVCodec'
 2586 |     if(codec && codec->supported_framerates){
      |                 ~~~~~  ^
/wrkdirs/usr/ports/graphics/py-opencv-python-headless/work-py312/opencv-python-92/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:2587:37: error: no member named 'supported_framerates' in 'AVCodec'
 2587 |         const AVRational *p= codec->supported_framerates;
      |                              ~~~~~  ^
5 errors generated.
*** Error code 1

Downstream bug report: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=297370

Start by inspecting opencv/modules/videoio/src/cap_ffmpeg_hw.hpp around line 760 and cap_ffmpeg_impl.hpp around line 2586, then reproduce the headless build against FFmpeg 9.0. Check the relevant FFmpeg API changes and verify that the build completes without the reported AVCodec member errors.