DM-55493: 0.7.0 changelog for release

[jonathansick]

Summary

Adds the 0.7.0 changelog entry for the upcoming release, covering the ~20 commits since 0.6.0 (2023-10):

• Full ruff adoption (retiring black, flake8, isort) — DM-55493
• Routine pre-commit hook version refresh
• GitHub Actions version bumps (actions/checkout, pre-commit/action, lsst-sqre/build-and-publish-to-pypi)
• A small typing cleanup
• Several older Neophile-driven pre-commit bumps that had accumulated before the ruff migration

Note: templatekit's version is derived from git tags via setuptools_scm (dynamic = ["version"] in pyproject.toml), so no hardcoded version string needed changing.

Note: the dependencies.yaml workflow still runs lsst-sqre/run-neophile@v1 — I did not find a commit switching it to manual dependency bumps, so the changelog does not claim that change happened.

Jira: DM-55493

Test plan

• Human review of changelog wording for accuracy against the full ~2.9-year history
• Confirm 0.7.0 is the intended version (minor bump for the ruff/tooling change)
• Merge, tag 0.7.0, and cut the GitHub release only after review (not done here)