Sync loop path to diff files in .mergin folder exceeds 260 characters

User encountered an issue where they synced their project and the plugin entered a sync loop that created 100s of versions of the project within a few minutes without the user realising what had happened.

This appears to have been triggered by the project being stored in a directory with a long file path. Though the project directory and files were within the 260 character limit for Windows, some of the diff files in the .mergin folder exceeded this limit. The missing diff file causes the plugin to fail to create a changeset and the plugin continues to re-sync, creating new project versions, until the user kills the app.

This is related to ticket (Lutra internal use only): https://odoo.lutraconsulting.co.uk/odoo/helpdesk.ticket/helpdesk.ticket/16516