v8.1.1 (23 March 2020)

v8.1.1 (23 March 2020)

- Use ``winkerberos`` dependency on Microsoft Windows platform
  (@mtg-edmund-tse)
- Setting rename in config file: ``use_mod_kerb`` -> ``use_kerberos``
- Bug-fix: don't fall back to user/pass if kerberos is configured
- Bug-fix: send correctly formatted authorization request header,
  per RFC-4459
- Bug-fix: properly authenticate with Kiwi TCMS via kerberos ticket
  if requested to do so
- Start sending ``User-Agent: tcms-api/<version>`` for all requests
- Enable integration testing with and without Kerberos
- Enable testing on Windows