Notable changes:

• uv_metrics_idle_time() and UV_METRICS_IDLE_TIME have been added for measuring the amount of time the event loop spends idle.
• uv_udp_using_recvmmsg() has been added to determine if a buffer is large enough for multiple datagrams should be allocated in the allocation callback of uv_udp_recvstart().
• On MinGW, the installation location has been updated to match Unix systems rather than Windows.
• uv_fs_copyfile() now tries to use copy_file_range() when possible.
• The test suite is now reported to pass on Darwin ARM64 (Apple Silicon).
• uv_{get,set}_process_title() now returns an error on platforms where uv_setup_args() is required, but has not yet been called.
• The _POSIX_PATH_MAX constant is no longer used, which could lead to buffer overflows in uv_fs_readlink() and uv_fs_realpath().