v2.1.1

Fixed

• The exec component would sometimes fail on Python 3.9 because it wasn't
  catching the right exception.
• The exec component would sometimes issue an empty write to stdout/stderr
  which (at least in theory) could confuse the consumer of those streams.
• Fixed syntax errors in the gwf run and gwf status commands such
  that they now work in Python 3.8 again.

Added

• We now test correctly on all supported Python versions.