Install setuptools_scm via pip to fix vcs_versioning build failure

[andystaples]

Problem

Follow-up to #609. With setuptools upgraded to >= 69.3.0, the build now fails earlier with:

File ".eggs/setuptools_scm-10.2.0-py3.10.egg/setuptools_scm/__init__.py", line 8, in <module>
    from vcs_versioning import Configuration
ModuleNotFoundError: No module named 'vcs_versioning'

Root cause

setup.py declares setup_requires=['setuptools_scm'], which triggers setuptools' deprecated fetch_build_eggs path. That path fetches setuptools_scm as an egg into .eggs/ but does NOT install its transitive dependency vcs_versioning (split out as a separate distribution in setuptools_scm 10.x). Importing setuptools_scm then fails.

This did not surface in #609's local simulation because that run happened to have setuptools_scm already pip-installed (which also pulls vcs_versioning), masking the egg-fetch path the agents actually use.

Fix

Install setuptools_scm via pip in both pipelines. Once the requirement is already satisfied in the environment, setuptools skips the deprecated egg-fetch entirely, and pip has resolved vcs_versioning transitively.

Verification

Reproduced the agent path in a clean Python 3.10 venv (requirements + setuptools>=69.3.0 wheel, no explicit setuptools_scm) -> ModuleNotFoundError: No module named 'vcs_versioning'. After adding pip install setuptools_scm the build succeeds and still emits the PEP 625 normalized azure_functions_durable-*.tar.gz.

[andystaples]

@microsoft-github-policy-service rerun