Pin cloudpickle to 2.1.0 in preparation for Beam 2.42.0 release.

[tvalentyn]

Addresses #23119 for 2.42.0 milestone.

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[tvalentyn]

Cherrypicks: #23120

[codecov]

Codecov Report

Merging #23121 (5763313) into release-2.42.0 (3d64d63) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@                Coverage Diff                 @@
##           release-2.42.0   #23121      +/-   ##
==================================================
- Coverage           73.58%   73.58%   -0.01%     
==================================================
  Files                 716      716              
  Lines               95301    95301              
==================================================
- Hits                70129    70127       -2     
- Misses              23876    23878       +2     
  Partials             1296     1296              

Flag	Coverage Δ
python	83.40% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
.../python/apache_beam/transforms/periodicsequence.py	98.38% <0.00%> (-1.62%)	⬇️
sdks/python/apache_beam/io/localfilesystem.py	90.97% <0.00%> (-0.76%)	⬇️
sdks/python/apache_beam/runners/direct/executor.py	96.46% <0.00%> (-0.55%)	⬇️
...beam/runners/portability/local_job_service_main.py	14.43% <0.00%> (-0.42%)	⬇️
sdks/python/apache_beam/transforms/combiners.py	93.05% <0.00%> (-0.39%)	⬇️
...eam/runners/interactive/interactive_environment.py	91.71% <0.00%> (-0.31%)	⬇️
...ks/python/apache_beam/runners/worker/sdk_worker.py	88.94% <0.00%> (-0.16%)	⬇️
...beam/runners/portability/expansion_service_main.py	0.00% <0.00%> (ø)
sdks/python/apache_beam/runners/common.py	88.71% <0.00%> (+0.12%)	⬆️
...hon/apache_beam/runners/worker/bundle_processor.py	93.54% <0.00%> (+0.12%)	⬆️
... and 3 more

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[lostluck]

LGTM