v2.1.1

Changed

• The command line ends through duho.run: Ctrl-C ends with status 130 and a closed
  standard output with status 1, both without a traceback. --help, --version and a
  usage error still raise SystemExit.
• sslcontext list and sslcontext probe take --format {text,json} besides --json.
  Their JSON is indented the same way; a non-ASCII character in it is now written as
  itself, not as a \uXXXX escape. The help text of --json now reads "Same as
  --format json".
• The cli extra needs duho>=0.7.8,<0.8 (was >=0.7.4).

Full Changelog: v2.1.0...v2.1.1