build: fix publish flow

[kikoso]

This PR adds the required id-token: write permission at the appropriate level, allowing the publishing workflow to run successfully.

There are currently no proper ways to run the GitHub actions locally before testing them, like act, which works half of the time, so it is a bit of a painful process. This can be verified by an admin by triggering the Release Please workflow or manually triggering the Publish workflow on a branch and checking if it fails with the same permission error.

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Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open a GitHub issue as a bug/feature request before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #59 🦕