Fix docker-compose for Development

[Brend-Smits]

Description

Docker-compose was broken due to the addition of persistence storage #159 in the Identity Server. I fixed it by adding a connection string to the IDS.
Tested this with @juliaslaats and @liekevdvoort and it now works for them.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• My code follows the style guidelines of this project
• I did not update API Controllers, if I did, I added/changed Postman tests
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I updated the changelog with an end-user readable description
• I assigned this pull request to the correct project board to update the sprint board

Steps to Test or Reproduce

Outline the steps to test or reproduce the PR here.
These steps will be used during release testing.

1. Follow getting-started docker guide

Link to issue

Closes: #234

[wotwot563]

Also maybe an improvement, we could use the container names instead of the ip addresses. this could enhance the readability of the docker compose file and remove possible ip conflicts etc.