ci: stop one duplicate wheel from cancelling every other platform

[theGreatHerrLebert]

What happened

The v0.4.2 release published Linux 3.11–3.13 and macOS arm64 3.12/3.13, then stopped. All three Windows jobs and macOS 3.11 were cancelled, so those platforms have no 0.4.2 wheel.

Because every imspy package in this release now requires imspy-connector>=0.4.2, installing the stack on Windows currently fails to resolve. Linux is fully covered, so the original report that prompted the release is unblocked.

Why

Two workflow bugs combined.

1. A guaranteed duplicate. macos-14 and macos-15 are both arm64, and both built with --target aarch64-apple-darwin — so they produce byte-identical wheel names. Whichever uploads second is always rejected:

Failed to upload "imspy_connector-0.4.2-cp312-cp312-macosx_11_0_arm64.whl" (6.6 MiB)
  Caused by: File already exists ('imspy_connector-0.4.2-cp312-cp312-macosx_11_0_arm64.whl' …)

2. Default fail-fast. That guaranteed-failing job then cancelled every platform still building. Windows takes longest, so Windows always loses.

This isn't new — the same signature appears on the models-v0.6.0 release back in May, which also shows Rust Binding: failure. It's been silently costing platforms wheels for months; it only became visible now because the pins make the connector mandatory.

Fix

• Drop the duplicate macOS runner (macos-15), keeping one arm64 builder.
• fail-fast: false — platforms publish independently; one failure can't cost another platform its wheel.
• maturin publish --no-sdist --skip-existing — an already-uploaded wheel is skipped instead of failing the job.
• Add workflow_dispatch, so a partially-published version can be completed by re-running against the same ref rather than cutting a new release. --skip-existing makes that safe to repeat.

Publishing the missing v0.4.2 wheels

A re-run of the existing release run would use the workflow as it was at the tag, so it would hit the same bug. Once this merges, the missing Windows and macOS-3.11 wheels can be published by dispatching this workflow against main — the connector source there is identical to the v0.4.2 tag, and --skip-existing will skip the wheels PyPI already has.

I have not dispatched anything; that's your call.

Note

No Intel macOS (x86_64) wheels are produced — before or after this change, the matrix is arm64-only. Flagging rather than changing it, since adding macos-13 is a separate decision.

https://claude.ai/code/session_01532ckxwR1fUorKF7CN66uA