ci(schema): add pr-write permissions for comments

[andrewazores]

Welcome to Cryostat3! 👋

Before contributing, make sure you have:

• Read the contributing guidelines
• Linked a relevant issue which this PR resolves
• Linked any other relevant issues, PR's, or documentation, if any
• Resolved all conflicts, if any
• Rebased your branch PR on top of the latest upstream main branch
• Attached at least one of the following labels to the PR: [chore, ci, docs, feat, fix, test]
• Signed all commits using a GPG signature

To recreate commits with GPG signature git fetch upstream && git rebase --force --gpg-sign upstream/main

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Related to #334