Update `prer` to use commit messages and or PR content so release notes can be generated

### Description of the problem / feature request:
Previously we were able to construct release notes by hovering over the commit hashes but GitHub has removed showing previews of the PRs linked to the commits.

The commit history on the PR branch can no longer be used to crate release notes easily

### Feature requests: what underlying problem are you trying to solve with this feature?
prer should automate or make it easy to view all the commit messages that resulted in the manifest changes. E.g. automate the release notes.

### Have you found anything relevant by searching the web?

Automating release notes via commit messages: https://www.conventionalcommits.org/en/v1.0.0/

La issue nomina `prer`, ma non indica file o test. Inizia individuando il codice che gestisce le modifiche al manifest e l’output della release, quindi determina come sono disponibili i messaggi dei commit o il contenuto della pull request; il lavoro è completo quando `prer` può mostrare o generare release notes per i commit alla base delle modifiche al manifest.

Scritto dal modello di indicizzazione a partire dal testo della issue.