v0.5.6: The `patch` a machine happens to have is now checked for being new enough, not just for being GNU

Fixed

• An old patch on PATH aborted on every repair inside a package, and
  nothing said why. GNU patch 2.5.9 fails an internal assertion when a hunk
  writes into a subdirectory, which is what a package-seeded implementation is
  made of. It is from 2002, and Strawberry Perl, the usual Perl distribution
  for Windows, installs it ahead of Git's copy on PATH. The existing guard
  only asks whether a patch is GNU, which this one is: it takes --fuzz and
  --dry-run without complaint and then dies with a dialog naming a line in
  patch's own C source, so a Windows user saw every FIX fail for a reason no
  message connected to the binary they never chose. qikly now asks each
  candidate for its version and steps over anything below 2.7, which finds the
  current GNU patch that Git for Windows ships under usr\bin even when
  another one comes first. A patch whose version cannot be read is still
  used, so nothing that works today stops working. The version is a
  preference rather than a veto: where no candidate is new enough, the first
  is still used, because an older patch refuses these flags outright and
  says so, and on macOS without gpatch that is Apple's own. The one refusal
  is a patch between 2.5 and 2.7, which accepts the flags and then aborts;
  there the error names each binary, its version, and the fix for the
  platform, since nothing else would connect the crash to the cause. Found on
  GitHub's own Windows runners, which preinstall Strawberry Perl.