Add agreement bucket to `run_app.sh`
Add agreement bucket to `run_app.sh`

Running the app without `DM_AGREEMENTS_BUCKET`
set causes the app to fail in various places
(such as the frameworks dashboard).
Setting the variable resolves the issue.

alphagov/digitalmarketplace-supplier-frontend,alphagov/digitalmarketplace-supplier-frontend,alphagov/digitalmarketplace-supplier-frontend,alphagov/digitalmarketplace-supplier-frontend