Update smoltcp requirement from 0.5 to 0.7

[dependabot-preview]

Updates the requirements on smoltcp to permit the latest version.

Changelog

Sourced from smoltcp's changelog.

0.7.0 - 2021-01-20

Minimum Supported Rust Version (MSRV) bumped from 1.36 to 1.40

New features

• tcp: Allow distinguishing between graceful (FIN) and ungraceful (RST) close. On graceful close, recv() now returns Error::Finished. On ungraceful close, Error::Illegal is returned, as before. (351)
• sockets: Add support for attaching async/await Wakers to sockets. Wakers are woken on socket state changes. (394)
• tcp: Set retransmission timeout based on an RTT estimation, instead of the previously fixed 100ms. This improves performance on high-latency links, such as mobile networks. (406)
• tcp: add Delayed ACK support. On by default, with a 10ms delay. (404)
• ip: Process broadcast packets directed to the subnet's broadcast address, such as 192.168.1.255. Previously broadcast packets were only processed when directed to the 255.255.255.255 address. (377)

Fixes

• udp,raw,icmp: Fix packet buffer panic caused by large payload (332)
• dhcpv4: use offered ip in requested ip option (310)
• dhcpv4: Re-export dhcp::clientv4::Config
• dhcpv4: Enable proto-dhcpv4 feature by default. (327)
• ethernet,arp: Allow for ARP retry during egress (368)
• ethernet,arp: Only limit the neighbor cache rate after sending a request packet (369)
• tcp: use provided ip for TcpSocket::connect instead of 0.0.0.0 (329)
• tcp: Accept data packets in FIN_WAIT_2 state. (350)
• tcp: Always send updated ack number in ack_reply(). (353)
• tcp: allow sending ACKs in FinWait2 state. (388)
• tcp: fix racey simultaneous close not sending FIN. (398)
• tcp: Do not send window updates in states that shouldn't do so (360)
• tcp: Return RST to unexpected ACK in SYN-SENT state. (367)
• tcp: Take MTU into account during TcpSocket dispatch. (384)
• tcp: don't send data outside the remote window (387)
• phy: Take Ethernet header into account for MTU of RawSocket and TapInterface. (393)
• phy: add null terminator to c-string passed to libc API (372)

Quality of Life™ improvements

• Update to Rust 2018 edition (396)
• Migrate CI to Github Actions (390)
• Fix clippy lints, enforce clippy in CI (395, 402, 403, 405, 407)
• Use #[non_exhaustive] for enums and structs (409, 411)
• Simplify lifetime parameters of sockets, SocketSet, EthernetInterface (410, 413)

Commits

• 80ba25d Bump version, update repo URLs
• 2650fc9 changelog: mention MSRV bump
• fe8507b Link to PRs in changelog.
• b7a2dbd Add CHANGELOG.md
• c9d1555 Update README.md with now-supported features.
• cc75437 Merge pull request #413 from smoltcp-rs/simplify-lifetimes-2
• 0c38674 Simplify EthernetInterface lifetimes.
• 43cf6ca Simplify SocketSet lifetimes
• 8aed248 Clarify docs of DeviceCapabilities MTU. Fixes #392
• 9d8dbbf Merge pull request #377 from MabezDev/subnet-local-broadcasts
• Additional commits viewable in compare view

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