Fix tox.ini -- Add missing psycopg dep for no-contenttypes env

[amureki]

Describe the change

• Added missing psycopg dependency for the postgresql-no-contenttypes factor
• Removed orphan postgresql-contenttypes dependency that had no matching environment

PR Checklist

• Change is covered with tests
• CHANGELOG.md is updated if needed

Summary by CodeRabbit

• Bug Fixes

  • Restored missing PostgreSQL adapter in test environments.
  • Ensured the "disable contenttypes" test setting actually prevents contenttypes from being enabled.

• Chores

  • Consolidated PostgreSQL-related test dependency specifications into a single alias.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Consolidates psycopg dependency entries in tox.ini so the no-contenttypes test env receives psycopg, updates CHANGELOG.md, and changes tests/conftest.py to treat USE_CONTENTTYPES as enabled only when the environment value equals "true" (case-insensitive).

Changes

Cohort / File(s)	Summary
Changelog CHANGELOG.md	Added Unreleased entries documenting the psycopg dependency fix and the USE_CONTENTTYPES test behavior fix.
Test configuration tox.ini	Merged two dependency entries into a single multi-name alias: replaced separate postgresql-psycopg3: psycopg and postgresql-contenttypes: psycopg with postgresql-psycopg3,postgresql-no-contenttypes: psycopg so psycopg installs for the no-contenttypes variant.
Test runtime logic tests/conftest.py	Changed USE_CONTENTTYPES handling to enable contenttypes only when USE_CONTENTTYPES.lower() == "true", altering truthiness semantics for the env var and affecting whether django.contrib.contenttypes and django.contrib.auth are appended to INSTALLED_APPS.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I hopped through tox with nimble feet,

merged deps so tests could meet.
A tiny tweak, a clearer cue —
"true" lets contenttypes come through.
Cheers from a rabbit, code now neat!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding missing psycopg dependency for the no-contenttypes environment in tox.ini.

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✨ Finishing touches

• 📝 Generate docstrings

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