Never mark spam on restore

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Please confirm the following:
* I have upgraded to the latest GYB release from https://github.com/jay0lee/got-your-back/releases and I still have this issue.
* I am typing the command as described in the GAM Wiki at https://github.com/jay0lee/got-your-back/wiki

Full steps to reproduce the issue:
1. Back up from one account
2. Restore to another account

Expected outcome (what are you trying to do?): All messages restored with similar structure.

Actual outcome (what errors or bad behavior do you see instead?): Thousands of legitimate messages from the first account classified as spam in the second account.

Unfortunately Gmail won't let me bulk mark them all "not spam", either, so this is a whole lot of repetitive clicking to rectify.

I see the Gmail API has a `neverMarkSpam` option on some endpoints, but I can't tell if it's available on the endpoint you're using because I can't read Python. 🙃