fix(actions): reintroduce token to checkout repo in release workflow

[dreamorosi]

Description of your changes

Currently the on-release workflow is failing due to the following error:

remote: error: GH006: Protected branch update failed for refs/heads/main.        
remote: error: At least 2 approving reviews are required by reviewers with write access.

After a bit of research it appears that this is happening because the workflow is being executed with an identity that doesn't have enough rights to merge onto main, which is a protected branch.

As a part of #805 I removed the token as I didn't know the impact it would have. At the same time we haven't noticed since because we haven't made any release in the past few weeks.

This pr reintroduces the token into the workflow, as well as adding a comment that documents why it's there.

Resources:

• https://www.paulmowat.co.uk/blog/resolve-github-action-gh006-protected-branch-update-failed
• https://github.community/t/how-to-push-to-protected-branches-in-a-github-action/16101/9

How to verify this change

AFAIK the only reasonably straightforward way to verify this PR is to merge it & try to execute the modified workflow.

Related issues, RFCs

#805

PR status

Is this ready for review?: YES
Is it a breaking change?: NO

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• My changes generate no new warnings
• The code coverage hasn't decreased
• Any dependent changes have been merged and published in downstream module
• The PR title follows the conventional commit semantics

Breaking change checklist

N/A

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