libcamera: converter_v4l2_m2m: Add missing <set> include

`std::set` is directly used in the file, but not directly included.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/converter/converter_v4l2_m2m.cpp

@@ -10,6 +10,7 @@
 
 #include <algorithm>
 #include <limits.h>
+#include <set>
 
 #include <libcamera/base/log.h>
 #include <libcamera/base/signal.h>