fix: skip release-please job on chore release merge commits

[Copilot]

Summary

Added a commit-message guard to the release-please job so it does not run when a release PR merge commit is pushed to main.

Why

release-please generates merge commits with the message chore: release <version>. Without a guard, every such merge immediately triggers release-please again, causing it to open a new release PR right after the previous one was merged.

Before:

release-please:
  if: github.event_name == 'push'

After:

release-please:
  if: >-
    github.event_name == 'push' &&
    !startsWith(github.event.head_commit.message, 'chore: release')

Validation

• python -m ruff check .
• python -m ruff format --check .
• python -m pytest
• python -m build --sdist --wheel
• Not applicable — workflow YAML change only; no Python code modified.

Documentation

• Documentation was updated where needed.
• No documentation update was needed.

Scope

• This pull request is focused on one feature or fix.
• Tests were added or updated for functional changes.
• Assumptions, risks, or follow-up work are described below.

Risks or follow-up

The guard matches on prefix chore: release, which aligns with the commit message format release-please produces. If the release-please commit message format ever changes, this guard would need updating.

• Fixes Adjust Ci release please trigger #68

[spmse]

@copilot also see the workflow runs, e.g release workflow for release main (#64) which fails while building the docs etc

[Copilot]

@copilot also see the workflow runs, e.g release workflow for release main (#64) which fails while building the docs etc

I investigated run #28 (chore: release main (#64)) in detail. There were two distinct failures:

1. Spurious new PR opened after releasing – After creating the draft releases for PR chore: release main #64, release-please immediately ran its PR-creation phase. Because GitHub does not materialise git tags for draft releases, the tag core-v0.5.0 wasn't yet findable, so release-please treated all historical commits as unreleased and opened PR chore: release main #67.

2. build-documentation / build-release-evidence checkout failure – Both jobs tried actions/checkout ref: core-v0.5.0, but (again) GitHub only creates the git tag when a draft release is published – gh release edit --draft=false happens at the end of build-release-evidence, too late for the initial checkout.

Fixed in commit fix: skip PR phase on release commits and use SHA for checkout:

• skip-github-pull-request is now set to true whenever the push commit message starts with chore: release. Release-please still runs its release-creation phase (so draft releases and their eventual tags are created), but skips the PR-creation phase that was opening spurious follow-up PRs.
• core_sha (the packages/core--sha output from release-please) is now exposed as a job output and used for both build-release-evidence and build-documentation checkouts. The commit SHA is always resolvable immediately; the git tag is only needed for uploading artifacts to the release, which happens after checkout.