Unread email badge next to email folders are only refreshed on app restart

## What Happened
Unread email badges next to email folders are only updated on app start.
If I read the unread emails in a folder the badge of unread emails is not updated.
If I close and start the app again, then the badge of unread emails is updated with the right number of unread emails.

## Expected Behavior
Unread email badge next to email folders should be updated as soon as the emails in that folder are being read.

## Steps to Reproduce

1. Go to a folder in your email account with unread emails.
2. Read or mark read the unread emails. This should update the unread email badge right away.

### Logs
N/A

## Platform Information
elementary OS 6 Odin
Mail version: io.elementary.mail/focal,now 6.1.0+r613+pkg23~ubuntu6.1