opencv: fix build error on macOS

Fix : #1612 (closed)

The build fails on macos with the following error: /usr/local/Cellar/opencv/4.5.0_5/include/opencv4/opencv2/core/mat.hpp:2226:15: error: no template named 'initializer_list' in namespace 'std' Mat_(std::initializer_list<_Tp> values); fatal error: too many errors emitted, stopping now [-ferror-limit=] 35 warnings and 20 errors generated.