Vendor latest cloudpickle and loky

[ogrisel]

This should support Python 3.9 and also add support for physical core detection.

[codecov]

Codecov Report

Merging #1111 into master will decrease coverage by 0.90%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1111      +/-   ##
==========================================
- Coverage   94.52%   93.61%   -0.91%     
==========================================
  Files          47       47              
  Lines        6955     6956       +1     
==========================================
- Hits         6574     6512      -62     
- Misses        381      444      +63     

Impacted Files	Coverage Δ
joblib/parallel.py	96.45% <100.00%> (ø)
joblib/backports.py	44.73% <0.00%> (-39.48%)	⬇️
joblib/_memmapping_reducer.py	94.33% <0.00%> (-2.27%)	⬇️
joblib/_parallel_backends.py	93.75% <0.00%> (-1.96%)	⬇️
joblib/test/test_memmapping.py	97.33% <0.00%> (-1.91%)	⬇️
joblib/test/test_parallel.py	95.39% <0.00%> (-1.78%)	⬇️
joblib/hashing.py	89.38% <0.00%> (-1.77%)	⬇️
joblib/pool.py	86.17% <0.00%> (-1.63%)	⬇️
joblib/disk.py	90.47% <0.00%> (-1.59%)	⬇️
joblib/logger.py	85.52% <0.00%> (-1.32%)	⬇️
... and 4 more

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