fix(ci): keep skipped package releases green and stop sending target_commitish (release-1.12.0) (#14650)

fix(ci): keep skipped package releases green and stop sending target_commitish

The four determine-*-version jobs ended their "already on PyPI" branch with
`exit 1`, so a release with nothing new to publish reported red even though
every consumer gates on `outputs.skipped` rather than on the job result. Emit
the version, mark the job skipped, and exit clean.

Create Release passed `commit:` (target_commitish) unconditionally. GitHub
ignores that field once the tag exists, but sending it still runs the create
endpoint's workflow-permission check against the resolved commit, and an
Actions token is never granted the Workflows permission. The 1.11.4 release
failed five attempts with "403 Resource not accessible by integration" while
holding contents: write. Resolve the sha only while the tag is still missing,
and spell out the release job's permissions.