42333: vendor: bump pebble to 1b3c610a92c005ff15507aafbb0d69263abaa717 r=petermattis a=petermattis

Pick up fixes for range tombstone handling in `mergingIter` and an
infinite seek loop in `mergingIter` caused by a bug in `levelIter`.

Release note: None

Co-authored-by: Peter Mattis <petermattis@gmail.com>