Python: Fix dependencies for durabletask

[larohra]

Motivation and Context

• Add python.dateutil dependency for durabletask package and remove unnecessary typing from azurefunctions package.
• Fix the requirements.txt for durabletask package.

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	16249	2024	87%

report-only-changed-files is enabled. No files were changed during this commit :)

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3674	221 💤	0 ❌	0 🔥	1m 9s ⏱️

[Copilot]

Pull request overview

This PR fixes Python dependency management for the durabletask and azurefunctions packages by correctly placing python-dateutil where it's actually used and removing unnecessary type stub dependencies.

Changes:

• Added python-dateutil>=2.8.0 as a runtime dependency to the durabletask package (where it's actually imported and used)
• Removed types-python-dateutil from azurefunctions package dev dependencies (since dateutil is not used there)
• Updated all durabletask sample requirements.txt files to use the published package agent-framework-durabletask instead of editable local installs

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated no comments.

File	Description
python/uv.lock	Updated lockfile reflecting the dependency changes for both packages
python/packages/durabletask/pyproject.toml	Added python-dateutil>=2.8.0 to runtime dependencies
python/packages/azurefunctions/pyproject.toml	Removed unnecessary types-python-dateutil from dev dependencies
python/samples/getting_started/durabletask/*/requirements.txt	Updated 7 sample requirements files to use published package instead of editable installs