Docs - Fix missing filename from import script

What does this MR do?

This fixes an issue with the Python import project example.

In its current form, the script does create the project, but none of the files, issues, MRs etc.

In the Sidekiq logs, the user can find this error gitlab-foss#50944 (closed)

The fix is to send a filename with .tar.gz so the file is accepted as mentioned here gitlab-foss#50944 (comment 101737263)

Related issues

Author's checklist

• Follow the Documentation Guidelines and Style Guide.
• If applicable, update the permissions table.
• Link docs to and from the higher-level index page, plus other related docs where helpful.
• Apply the ~Documentation label.

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3. Maintainer

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