Fix: Changing Server Timezone

[GODrums]

Motivation

We want to change the timezone of the server to correctly schedule CRON-jobs, such as the scheduled Slack message.

Description

This PR sets the timezone to Europe/Berlin, which resolves to UTC+1/+2 handling daylight saving time automatically.
Has been tested as preview deployment on the server:

Testing Instructions

Nothing to test really

Checklist

General

• PR title is clear and descriptive
• PR description explains the purpose and changes
• Code follows project coding standards
• Self-review of the code has been done
• Changes have been tested locally
• Screenshots have been attached (if applicable)
• Documentation has been updated (if applicable)

Server (if applicable)

• Code is performant and follows best practices
• No security vulnerabilities introduced
• Proper error handling has been implemented
• Added tests for new functionality
• Changes have been tested in different environments (if applicable)