Refresh Python SDK dependencies

[kvz]

Why

Dependabot has several narrow Python dependency PRs open. This consolidates the safe dependency refresh into one tested, release-ready PR while keeping the SDK runtime floor at Python 3.9, because package metadata, README, and CI all still claim/test Python 3.9 support.

What

• Bumped the package version to 1.0.4 across pyproject.toml, transloadit/__init__.py, and the version header test.
• Refreshed the Poetry lockfile, including aiohttp 3.13.5, idna 3.15, pygments 2.20.0, Python-version-specific requests updates, and tuspy 1.1.0.
• Updated dev/docs tooling to Python 3.9-compatible majors: pytest 8.4, pytest-cov 7.1, Sphinx 7.4, and sphinx-autobuild 2024.10.
• Removed obsolete six usage from runtime/tests now that the SDK supports Python 3.9+.
• Replaced deprecated datetime.utcnow() usage with timezone-aware UTC.
• Updated docs requirements/config and added a concrete 1.0.4 changelog entry.
• Supersedes Bump aiohttp from 3.13.3 to 3.13.4 #51, Bump idna from 3.7 to 3.15 #52, and Bump pygments from 2.18.0 to 2.20.0 #53.

Held back

• pytest 9 requires Python >=3.10.
• Sphinx 8/9 and sphinx-autobuild 2025.x require newer Python floors than the SDK currently declares.
• The Python floor may be reconsidered in a future major SDK release, but this refresh intentionally keeps it stable.

Validation

• poetry check
• poetry run pytest --cov=transloadit tests
• poetry run python -m sphinx -b html docs/source /tmp/python-sdk-sphinx-html
• DOCKER_PLATFORM=linux/arm64 ./scripts/test-in-docker.sh --python 3.9 -- pytest --no-cov tests
• git diff --check

Release notes

• Added CHANGELOG.md entry for 1.0.4 / 2026-05-20.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.60%. Comparing base (4c84387) to head (014f00b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #54      +/-   ##
==========================================
- Coverage   87.03%   86.60%   -0.44%     
==========================================
  Files           7        7              
  Lines         216      209       -7     
  Branches       27       19       -8     
==========================================
- Hits          188      181       -7     
  Misses         28       28              

Flag	Coverage Δ
unittests	86.60% <100.00%> (-0.44%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.