replace requests with urllib

[pmeier]

Closes #4941. With this we lose the ability to send the confirm token, since urllib has no support for it. I've checked all of our GDrive resources in the datasets and none required it. TBH, I don't think we ever had a case where it was needed.

In case the confirm token is indeed needed in the future, I suggest we hard depend on requests, since urllib is only meant for very simple uses cases.

cc @pmeier

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[NicolasHug]

Thanks @pmeier , LGTM when green

[pmeier]

While working on #5035, I realized we unfortunately sometimes need the confirm token. This happens if GDrive is unable to perform a virus scan and is asking the user for confirmation to proceed. This regularly happens for large files. Thus, I would follow my suggestion in the top comment to revert this PR and afterwards make requests a hard dependency.

[datumbox]

@pmeier There were a couple of PRs that removed the functionality (including cleaning up a private method), so clicking the revert button here wont do the trick. You might need to do a bit more to undo the change. Concerning adding requests as a hard dependency, I'm OK with it.