doc: replace URL action example with form The example to provide a link to take or resolve an item was broken. Roundup has required a POST not GET for changes to the database for a while. This example was never fixed. Replaced a link using GET with a POSTed form. This changes the activating element from a link to a button. The button could be restyled as a link using CSS I think. The original example was also not canonical. It used :action rather than the canonical @action.

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

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

except ImportError:
    from datetime import datetime

    def utcnow():
        return datetime.utcnow()