MSPileupData broken in python 3.9

[khurtado]

Impact of the bug

When importing pymongo from MSPileupData with python 3.9, we get errors due to crypto versions in this version.

Describe the bug
When importing MSPileupData:

File "/home/cmsbld/WMCore/src/python/WMCore/MicroService/MSPileup/MSPileup.py", line 14, in <module>
    from WMCore.MicroService.MSPileup.MSPileupData import MSPileupData

It gets stuck here:

WMCore/src/python/WMCore/MicroService/MSPileup/MSPileupData.py

Line 15 in 4e0759d

from pymongo import IndexModel, errors

with the following error:

    from WMCore.MicroService.MSPileup.MSPileupData import MSPileupData
  File "/home/cmsbld/WMCore/src/python/WMCore/MicroService/MSPileup/MSPileupData.py", line 15, in <module>
    from pymongo import IndexModel, errors
  File "/usr/local/lib64/python3.9/site-packages/pymongo/__init__.py", line 105, in <module>
    from pymongo.mongo_client import MongoClient
  File "/usr/local/lib64/python3.9/site-packages/pymongo/mongo_client.py", line 59, in <module>
    from pymongo import (
  File "/usr/local/lib64/python3.9/site-packages/pymongo/uri_parser.py", line 23, in <module>
    from pymongo.client_options import _parse_ssl_options
  File "/usr/local/lib64/python3.9/site-packages/pymongo/client_options.py", line 26, in <module>
    from pymongo.pool import PoolOptions
  File "/usr/local/lib64/python3.9/site-packages/pymongo/pool.py", line 60, in <module>
    from pymongo.network import command, receive_message
  File "/usr/local/lib64/python3.9/site-packages/pymongo/network.py", line 24, in <module>
    from pymongo import _csot, helpers, message, ssl_support
  File "/usr/local/lib64/python3.9/site-packages/pymongo/ssl_support.py", line 22, in <module>
    import pymongo.pyopenssl_context as _ssl
  File "/usr/local/lib64/python3.9/site-packages/pymongo/pyopenssl_context.py", line 27, in <module>
    from OpenSSL import SSL as _SSL
  File "/usr/local/lib/python3.9/site-packages/OpenSSL/__init__.py", line 8, in <module>
    from OpenSSL import crypto, SSL
  File "/usr/local/lib/python3.9/site-packages/OpenSSL/crypto.py", line 1550, in <module>
    class X509StoreFlags(object):
  File "/usr/local/lib/python3.9/site-packages/OpenSSL/crypto.py", line 1568, in X509StoreFlags
    NOTIFY_POLICY = _lib.X509_V_FLAG_NOTIFY_POLICY

A new version of PyOpenSSL may be required to fix this:
https://stackoverflow.com/questions/73830524/attributeerror-module-lib-has-no-attribute-x509-v-flag-cb-issuer-check

How to reproduce it
Run MSManager unit tests:
https://cmssdt.cern.ch/dmwm-jenkins/view/WMCore%20Docker/job/WMCore-Unittest-Baseline-khurtado2/48/testReport/junit/WMCore_t.MicroService_t.MSManager_t/MSManagerTest/test_services/

Expected behavior
Pymongo should be imported normally.

Additional context and error message
Related issue:
#11978