www/py-flask-login: Update to 0.6.2

py-flask-login 0.5 is broken with recent werkzeug 2.1.
Update to 0.6.2

PR: 265580
Reported by: fcharlier@ploup.net
Approved by: andrej@ebert.su (maintainer)

(cherry picked from commit 522dbcf83c046ec7e8ce433a1a75e89282bbf196)