Use mysqlclient instead of mysql-python

This PR swaps out mysql-python with mysqlclient in the requirements, the latter is available for python3 while the former is not.

added 12 commits

• 10150de9...62cc6ad3 - 11 commits from branch lscsoft:master
• 0c07a6ca - requirements: use mysqlclient instead of mysql-python

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added 29 commits

• 0c07a6ca...223208d0 - 28 commits from branch lscsoft:master
• a7472889 - requirements: use mysqlclient instead of mysql-python

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merged