- update to 6.2.9:
* For some reason, 6.2.8 release was incomplete. Let's try again.
* In Python 3.9, "find_unused_port" has been moved to
"test.support.socket_helper". Reported by Michał Górny.
* If we use "set_get_returns_none()" in the environment,
the value could not be correctly inherited by the child
databases. Reported by Patrick Laimbock and modern GCC
warnings.
* If you install this library under Python 3 >= 3.6, let
you know this is a legacy library and urges you to
migrate to "berkeleydb" library.
* Update copyright notices.
* https links.
* Fix Python 3 deprecation warning.
Notified by Arthur Gautier.
* Fix compilation Python 3.8 deprecation warnings.
* Fix compilation Python 3.9 deprecation warnings.