[Discuss-gnuradio] The `next` branch is going away

[CEL]

Hi, most magnificient SDR project,

because we're done with the merge of `next` into `master`, I'd like to
delete the former branch from our reference repository.

Unlike the old `maint` branch, no maintainer should have based anything
on the `next` branch, so I don't expect anyone's work flow to break due
to that deletion.

If you have any concerns you'd like to share, please do so!

If nothing surprising happens, the deletion will happen on the first of
November, 15:00 UTC.

Best regards,
Marcus

PS: I have to thank Derek for raising this with me; generally, if
anyone has something code maintenance-wise to share with me: my inbox
is all yours.