Fix ownership for /start-flower script in production Dockerfile

[SukiCZ]

Description

Fixing a bug which seems like a missing a small typo. I needed to apply these changes to production env to be able to start Flower

Checklist:

• I've made sure that tests are updated accordingly (especially if adding or updating a template option)
• I've updated the documentation or confirm that my change doesn't require any updates

The documentation doesn't need to be updated but I don't know how to test such change (it works on production tho)

Rationale

Fix #4602

This project is optionally shipped with Flower which doesn't run in production without this change. This seems like a small typo as other files are changing ownership to Django user. I hope I'm not missing something.

Thanks for a great project BTW ❤️

EDIT: I could add some small test suite for Flower if requested (just need more time) 🤞🏿

[browniebroke]

Good catch. Wondering how it's been broken all this time. Oh well...

[browniebroke]

Regarding testing, although I wish I had a better answer, there isn't much we can do right now, so don't worry about it.