CI: single source of truth

[GarethCabournDavies]

This is an attempt to have single sources of truth defined for the CI workflows. As a few of the workflows use the same information, it would be good to reuse it without the repetition across files.

Standard information about the request

This change follows style guidelines (See e.g. PEP8), has been proposed using the contribution guidelines

Motivation

Single source of truth

Contents

Add a new GitHub actions, to be called by the workflows. This defines a single source of truth which is then inherited by the other workflows

Testing performed

this seems to work in the act tests performed, but these have not been extensive

• The author of this pull request confirms they will adhere to the code of conduct

[Copilot]

Pull request overview

This PR introduces a reusable GitHub Actions workflow intended to centralize shared CI defaults (e.g., Python version, cache keys/paths) and updates existing workflows to consume those outputs, reducing repetition across workflow files. It also includes a few small cleanups of unreachable code and adjusts the search example’s data download script to try using a local cache.

Changes:

• Added .github/workflows/workflow-defaults.yml reusable workflow to publish shared outputs (Python version, cache key(s), paths) and perform some caching.
• Updated multiple CI workflows to call workflow-defaults.yml and reference its outputs instead of hardcoding values.
• Removed unreachable code in a couple of Python modules and updated examples/search/get.sh to avoid re-downloading files when already present.

Reviewed changes

Copilot reviewed 12 out of 14 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
pycbc/scheme.py	Removes unreachable break after return.
pycbc/distributions/joint.py	Removes unreachable assignment after early return.
pycbc/__init__.py	Adds pylint suppression for an intentionally-unused argument in formatTime.
examples/search/get.sh	Adds “use local cache if present” logic for frame downloads.
.github/workflows/workflow-tests.yml	Adds defaults workflow usage and attempts to consume its outputs.
.github/workflows/workflow-defaults.yml	New reusable workflow exporting defaults and attempting to manage caches.
.github/workflows/tmpltbank-workflow.yml	Uses defaults workflow output for Python version.
.github/workflows/search-workflow.yml	Adds restore-cache steps and uses defaults workflow output for Python version.
.github/workflows/mac-test.yml	YAML indentation/formatting adjustments.
.github/workflows/inference-workflow.yml	Uses defaults workflow output for Python version.
.github/workflows/distribution.yml	YAML indentation/formatting adjustments.
.github/workflows/check_code.yml	Reworks linter workflow and uses defaults workflow output for Python version.
.github/workflows/basic-tests.yml	Uses defaults workflow output for LAL data path and adds defaults workflow dependency.
.github/workflows/bank-compress-workflow.yml	Uses defaults workflow output for Python version.

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[GarethCabournDavies]

Note that here I have included a few things which weren't used everywhere, but I don think it is too expensive to run these install as well?

[GarethCabournDavies]

The - in GitHub variables can sometimes be misconstrued as negation, so underscores are safer