[DX] Added django-debug-toolbar as a dev dependency

[calumbell]

Description

This PR adds the Django Debug Toolbar to our list of development dependencies. This package has been extremely helpful in identifying N+1 errors on the API and is well worth having installed as default.

How was this tested

• (Local) Changing OPEN5E_DEBUG environment variable to False to confirm that the toolbar didn't run outside of debug mode.
• (Local) Run pytest to make sure the toolbar didn't interfere with it.

Pending to see whether the the toolbar is able to get out of the way correctly during CI tests. Standby.

[calumbell]

Alright, looks like CI is failing. After a brief investigation the problems appears to be on the Docker image build step:

#10 ERROR: process "/bin/sh -c uv sync --frozen --no-dev --no-install-project" did not complete successfully: exit code: 2
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 > [builder 4/7] RUN uv sync --frozen --no-dev --no-install-project:
0.184 error: Required uv version `>=0.10` does not match the running version `0.9.30`
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Looks like some kind of uv version mismatch. Will investigate further later this week.