v1.7.1

The first release of 1.7 on GitHub, crates.io and the package channels.
v1.7.0 was tagged but not published there: three of its integration tests
failed where sping may not open an ICMP socket, as in Nix's Linux build
sandbox and on GitHub's Ubuntu runner. Its binaries had no defect, and the
code of 1.7.1 is the same. What 1.7 brings, in detail under v1.7.0 in CHANGELOG.md:

• --diagnose (experimental): when the target stops answering, sping probes
  further on its own (the other address family, TCP 443 and 80, a bounded
  traceroute) and says what still answers.
• The name's lookups as evidence: a lookup that fails while the WAN
  reference answers, or that gives no address of the family probed.
• Context changes while monitoring: context changed 00:03 ago: interface eth0 → wlan0, for the interface, source, prefix, default gateway and
  target class.
• Fixes on macOS (echo replies matched by identifier for IPv4 too), for a
  target routed through an interface without an address of its family, and
  for the views and options that could leave sping stuck or ignore what it
  was told (--view table with one target, several targets piped, a
  misspelt --view, -o without --batch).

Fixes

• Tests: the two that drive the live views from a pseudo-terminal, and the
  one with several targets piped, needed an ICMP socket and failed without
  one. Where sping may not open one they now say so and skip what needs
  probes, as the other tests that need ICMP already did.