fix to allow mutations to actually occur to an individual

[jgh9094]

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What does this PR do?

When experimenting with TPOT2 and only allowing mutations to occur, no variation would be applied to the parents. This is because the var_op was 'mutate', not 'mutation'. Additionally, we needed to send an individual to the copy_and_mutate function, not a numpy array. This fix does all that.

Where should the reviewer start?

tpot2/population.py -> create_offspring2()

How should this PR be tested?

Any background context you want to provide?

What are the relevant issues?

[you can link directly to issues by entering # then the number of the issue]

Screenshots (if appropriate)

Questions:

• Do the docs need to be updated?
• Does this PR add new (Python) dependencies?