build: replace verstion extraction via set to use python The version of roundup was extracted from roundup/__init__.py by sed. It is used to label the roundup.pot template file. Replaced the sed setup by importing roundup and printing the __Version__ variable. This should be less fragile to spacing and other changes.

# https://issues.roundup-tracker.org/issue2551278
# datetime.utcnow deprecated
try:
    from datetime import UTC, datetime

    def utcnow():
        return datetime.now(UTC)

except ImportError:
    from datetime import datetime

    def utcnow():
        return datetime.utcnow()