Fix indentation in Dependabot config file
Fix indentation in Dependabot config file

I made a mistake in https://github.com/alphagov/digitalmarketplace-admin-frontend/pull/743: 

`The property '#/updates/1/schedule' contains additional properties ["ignored_updates"] outside of the schema when none are allowed`
alphagov/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend