[DEPR] ``pick_fastest`` needs to return ``None`` instead of empty ``Lap``

[theOehrly]

Laps.pick_fastest currently returns an empty Lap object in case there is no lap or no lap that meets the criteria for fastest lap.

Starting from v3.3 this should return None instead. The corresponding deprecation warning was added in #476.

See also: #472, #472 (comment)

This issue serves as a reminder to change this for v3.3

[theOehrly]

Change delayed because a DeprecationWarning was accidentally used (not shown to users by default) instead of a FutureWarning (shown to users by default).