This commit fixes error when updating multiple confluence attachments

[fkgruber]

Description

This PR fixes the problem described in #12558. Essentially you can't update more than 1 attachment at a time because you get a 500 error. The issue appears to be fixed if you upload attachments one at a time on a for loop with a delay im between.

Checklist

I have (if applicable):

• [ X] filed a contributor agreement.
• [ X] referenced the GitHub issue this PR closes
• updated the appropriate changelog in the PR
• ensured the present test suite passes
• added new tests
• created a separate documentation PR in Quarto's website repo and linked it to this PR

[posit-snyk-bot]

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[cscheid]

@cderv You added yourself as a reviewer. I think this is good to merge (there might be a better way that avoids the first delay if there's a single attachment, but I think this is fine). We do need a changelog entry, though.

[cderv]

Thanks ! I rebased on main, and adapted a few things.

I'll merge today