Use branch 3.0a6-cypclass_consume

This branch contains the latchang experimentations
regarding the type system for asynchronous computations,
used for the implementation of the KDTree.

cython @ 608c29a9

-Subproject commit 03d7c50ce1617f8cb49af8eab38fd8a7b640a633
+Subproject commit 608c29a9ab7b7803c900621424279a9e71fac106

requirements.txt

@@ -3,4 +3,4 @@ jupyter==1.0.0
 line-profiler==3.1.0
 matplotlib==3.4.1
 numpy==1.20.2
--e git+https://lab.nexedi.com/nexedi/cython.git@03d7c50ce1617f8cb49af8eab38fd8a7b640a633#egg=Cython&subdirectory=../../cython
+-e git+https://lab.nexedi.com/nexedi/cython.git@608c29a9ab7b7803c900621424279a9e71fac106#egg=Cython&subdirectory=../../cython