🍓 0.311.1

This release fixes an InvalidStateError crash in the DataLoader when a batch
load function raises an exception and some futures in the batch have already been
cancelled (e.g. due to client disconnection).

The error handler in dispatch_batch now skips cancelled futures before calling
set_exception, matching the guard that already exists in the success path
(added in #2339).

Releases contributed by @ben-xo via #4300