configure.ac: disable screen cap in macOS 15

macOS 15 drops support for the API we used for the screen capture in
favor of ScreenCaptureKit, the error is:
```
src/video_capture/screen_osx.c:109:28: error: 'CGDisplayCreateImage'
is unavailable: obsoleted in macOS 15.0 - Please use ScreenCaptureKit
instead.
  109 |         CGImageRef image = CGDisplayCreateImage(s->display);
      |                            ^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreGraphics.framework/Headers/CGDirectDisplay.h:383:33:
note: 'CGDisplayCreateImage' has been explicitly marked unavailable here
  383 | CG_EXTERN CGImageRef __nullable
  CGDisplayCreateImage(CGDirectDisplayID displayID)
```

configure.ac

@@ -2110,8 +2110,10 @@ AC_ARG_ENABLE(screen,
 
 case "$system" in
 	MacOSX)
-                screen_cap=yes
-                SCREEN_CAP_LIB="-framework CoreFoundation"
+                if test "$os_version_major" -lt 24; then # Darwin 24.0.0 is macOS 15
+                        screen_cap=yes
+                        SCREEN_CAP_LIB="-framework CoreFoundation"
+                fi
 	;;
         Windows)
                 screen_cap=$dshow