Update socket2 requirement from 0.3.16 to 0.4.0

[dependabot-preview]

Updates the requirements on socket2 to permit the latest version.

Changelog

Sourced from socket2's changelog.

0.4.0

Added

• New all feature: enables API that is not available on all tier 1 platforms.
• SockRef type: used to create a reference to an existing socket, e.g. std::net::TcpStream, making all methods of Socket available on it.
• Support for vectored I/O:
  • Socket::recv_vectored, Socket::recv_with_flags.
  • Socket::recv_from_vectored, Socket::recv_from_vectored_with_flags.
  • Socket::send_vectored, Socket::send_vectored_with_flags.
  • Socket::send_to_vectored, Socket::send_to_vectored_with_flags.
  • In the Read and Write implementations.
• Socket::new_raw, Socket::pair_raw and Socket::accept_raw methods that don't set common flags, such as the close-on-exec flag.
• Socket::accept4: accept4(2) system call.
• Socket::sendfile: the sendfile(2) system call.
• Socket::set_cloexec: set the close-on-exec flag on Unix.
• Socket::set_no_inherit: set inherit handle flag on Windows.
• Socket::set_nosigpipe: set SO_NOSIGPIPE on Apple targets.
• Socket::set_mark and Socket::mark, setting/getting the SO_MARK socket option.
• Socket::set_cpu_affinity and Socket::cpu_affinity, setting/getting the SO_INCOMING_CPU socket option.
• Socket::set_mss and Socket::mss, setting/getting the TCP_MAXSEG socket option.
• Socket::set_freebind and Socket::freebind, setting/getting the IP_FREEBIND socket option.
• Socket::bind_device and Socket::device, setting/getting the SO_BINDTODEVICE socket option.
• Adopted Mio's TCP keepalive API:
  • Socket::keepalive_time,
  • Socket::keepalive_interval,
  • Socket::keepalive_retries,
  • Socket::set_tcp_keepalive.
• Socket::is_listener getting the SO_ACCEPTCONN socket option.
• Socket::domain getting the SO_DOMAIN socket option.
• Socket::protocol getting the SO_PROTOCOL socket option.
• Socket::type getting the SO_TYPE socket option.
• Domain::for_address: the correct Domain for a std::net::SocketAddr.
• Type::nonblocking: set SOCK_NONBLOCK.
• Type::cloexec: set SOCK_CLOEXEC.
• Type::no_inherit: set HANDLE_FLAG_INHERIT.
• SockAddr::init: initialises a SockAddr.
• MaybeUninitSlice type: a version of IoSliceMut that allows the buffer to be uninitialised, used in Socket::recv_vectored and related functions.
• RecvFlags type: provides additional information about incoming messages, returned by Socket::recv_vectored and related functions.
• TcpKeepalive type: configuration type for a socket's TCP keepalive parameters.

... (truncated)

Commits

• b1479ff Release v0.4.0
• adf32da Use SO_LINGER_SEC for Socket::get/set_linger on macOS
• 559ba42 Fuchsia doesn't support sendfile
• 94c32b9 Release v0.4.0-alpha.5
• ca694de Change Socket::(set_)cpu_affinity to take an immutable reference
• 4f643fc Release v0.4.0-alpha.4
• c3b447e Add Socket::(set_)cpu_affinity
• 33da350 Release v0.4.0-alpha.3
• 4f22376 tests: add vsock test
• 07c7b37 unix: add SockAddr::vsock_address()
• Additional commits viewable in compare view

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