Fixed TypeError in QtScheduler

Fixes agronholm#687.

Updated actions

Dropped Python 2.7 from the list of supported Python versions

Relates to agronholm#666.

Dropped Python 2.7 from the list of supported Python versions

Relates to agronholm#666.

Added the release version

Added the release version

Removed a leftover check for pytz timezones

Fixes agronholm#599.

Added the publish workflow

Added the release version

Added the release version