Remove pytest-memray from test req, use only in CI

[michalk8]

closes #106

[codecov-commenter]

Codecov Report

Merging #107 (12d4e60) into main (5d48391) will increase coverage by 6.27%.
The diff coverage is 94.17%.

@@            Coverage Diff             @@
##             main     #107      +/-   ##
==========================================
+ Coverage   80.99%   87.27%   +6.27%     
==========================================
  Files          41       41              
  Lines        3630     3708      +78     
  Branches      423      431       +8     
==========================================
+ Hits         2940     3236     +296     
+ Misses        568      364     -204     
+ Partials      122      108      -14     

Impacted Files	Coverage Δ
ott/core/was_solver.py	100.00% <ø> (+5.00%)	⬆️
ott/geometry/low_rank.py	96.49% <90.00%> (+1.29%)	⬆️
ott/geometry/geometry.py	85.65% <90.19%> (+10.27%)	⬆️
ott/core/gromov_wasserstein.py	98.31% <100.00%> (+15.13%)	⬆️
ott/core/sinkhorn_lr.py	92.57% <100.00%> (+0.87%)	⬆️
ott/geometry/grid.py	91.15% <100.00%> (+0.97%)	⬆️
ott/geometry/pointcloud.py	83.66% <100.00%> (+16.65%)	⬆️
ott/core/sinkhorn.py	94.84% <0.00%> (+0.79%)	⬆️
... and 18 more