Money-to-prisoners-common

Contains:
• fix to ELK log formatting

Contains:
• rejection reason category definitions for security checks
• logging and error handling to allow Sentry.io to group messages better
• updated dependencies
• docker-compose notes

- https://github.com/ministryofjustice/money-to-prisoners-common/pull/415 Bumped transifex-client to work on Python 3.9 (locally)
- https://github.com/ministryofjustice/money-to-prisoners-common/pull/416 docker-compose: Ability to debug/attach to running containers

Includes:
• Updated dependencies
• Visual and print style fixes
• Compatibility with `mtp-api` asset building (that app still uses different paths for scripts and stylesheets)

Updated sign-up template and associated Form

All mtp-common components have been upgraded to use the [GOV.UK design system](https://design-system.service.gov.uk/).

Previously, we used [govuk-template](https://github.com/alphagov/govuk_template), [govuk-elements](https://github.com/alphagov/govuk_elements) and [govuk-frontend-toolkit](https://github.com/alphagov/govuk_frontend_toolkit) which are not maintained.