Cedar-backup3

* Add Sphinx configuration path to .readthedocs.yml.
* Set $SOURCE_DATE_EPOCH on build so sdist contents get sane timestamps.

* Pull in latest version of run-script-framework.
* Upgrade to poetry-dynamic-versioning v1.5.2 for minor fixes.
* Add .python-version in preferred order to support pyenv.
* Add missing runtime dependency on importlib-metadata.

* Migrate to Poetry v2 and project-managed Poetry plugins.
* Move configuration into pyproject.toml for coverage.
* Upgrade to gha-shared-workflowsv8 for Poetry v2 support.
* Update dependencies to match versions in Debian trixie.

* Add GitHub security policy in SECURITY.md.
* Pull in latest version of run-script-framework.
* Update dependencies to address Dependabot warnings.
* Upgrade to gha-shared-workflowsv7 with publish improvements.
* Change the default branch in GitHub from master to main.

* Pull in latest updates from run-script-framework.
* Simplify GHA integration with coveralls.io.
* Clarify that Debian stable is the target for dependencies.
* Update transitive dependencies to address Dependabot warnings.
* Add support for Python v3.13 and drop support for v3.9.
* Upgrade to Poetry v1.8.4 for official Python 3.13 support.
* Bump readthedocs build to python 3.10 and ubuntu-24.04.
* Adjust getFunctionReference() to use Python 3 callable().
* Convert to posixpath.isabs() to work around change in Python v3.13.

* Upgrade to Poetry v1.8.0 and make related adjustments.
* Disable Python keyring via poetry.toml.
* Update Poetry install instructions in DEVELOPER.md.
* Pull in latest version of run-script-framework.
* Upgrade to gha-shared-workflowsv4 with new Poetry setup.
* Add support for 'run outdated' and update dependencies.