[ffmpeg.wrap] Bump ffmpeg to meson-7.1

bestsource (R9-RC1) now require:
- libavcodec: >=61.19.0
- libavformat: >=61.7.0
- libavutil:>=59.39.0

Author: moi15moi

subprojects/ffmpeg.wrap

@@ -1,7 +1,7 @@
 [wrap-git]
 directory = ffmpeg
 url = https://gitlab.freedesktop.org/gstreamer/meson-ports/ffmpeg.git
-revision = meson-6.1
+revision = meson-7.1
 depth = 1
 
 [provide]