Bump/0.31

[Stef-Rousset]

🎩 Description

This PR updates the module to 0.31 version of Decidim.
It is not meant to be merged in master.

Testing

1. As an admin, go to a process > budgets and export projects as CSV
2. Modify the CSV to add one column 'paper_ballots_to_import', with integer values in it.
3. Go back to budgets and click on "Import paper ballots". Add your CSV file and click on 'Import'
4. See that the import has been performed as you have paper ballots count with value (screenshot one)
5. Go to the projects index and see that paper ballot counts are also displayed (screenshot two)

📌 Related Issues

• Related to https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=153225120&issue=OpenSourcePolitics%7Cintern-tasks%7C343

Tasks

• Update specs

📷 Screenshots

ONE

TWO

[BarbaraOliveira13]

LGTM