fix: re-add coroutines dependency

[pvannierop]

Description: This PR will re-add a dependency that was removed in the March 2025 security update.

Fixes: an error was reported when deleting subjects/users:

Caused by: java.lang.NoClassDefFoundError: kotlinx/coroutines/resactor/MonoKt

Checklist:

• The Main workflow has succeeded
• The Gatling tests have passed
• I have logged into the portal running locally with default admin credentials
• I have updated the README files if this change requires documentation update
• I have commented my code, particularly in hard-to-understand areas