[Bug]: Copilot PR approval label added incorrectly when author approves their own PR

### Issue Description

When a PR author who started a Copilot session approves their own Copilot-generated PR, the "approved" label should NOT be added automatically. The "approved" label should only be added when the approval comes from someone other than the PR author, as only non-author approvals can actually unblock merging.

### Expected Behavior

- If the PR author approves their own Copilot PR → do NOT add the "approved" label
- If someone else approves the Copilot PR → add the "approved" label

### Current Behavior

The "approved" label is being added even when the PR author approves their own Copilot PR.

### Related

- PR: https://github.com/actualbudget/actual/pull/6641
- Requested by: @MatissJanis