Python bindings upload to PyPi is broken

[penberg]

The release pipeline fails at the last minute:

🎛️ Running in non-interactive mode on CI
🚀 Uploading 18 packages
💥 maturin failed
  Caused by: 💥 Failed to upload "bindings" (4.1 KB)
  Caused by: IO Error
  Caused by: failed to read from file `/home/runner/work/limbo/limbo/bindings`: Is a directory (os error 21)
Error: The process '/home/runner/work/_temp/a43267ea-e7ac-4bee-a1b7-a380fa042d18/maturin' failed with exit code 1
    at ExecState._setResult (/home/runner/work/_actions/PyO3/maturin-action/v1/dist/index.js:1702:25)
    at ExecState.CheckComplete (/home/runner/work/_actions/PyO3/maturin-action/v1/dist/index.js:1685:18)
    at ChildProcess.<anonymous> (/home/runner/work/_actions/PyO3/maturin-action/v1/dist/index.js:1579:27)
    at ChildProcess.emit (node:events:519:28)
    at maybeClose (node:internal/child_process:1105:16)
    at ChildProcess._handle.onexit (node:internal/child_process:305:5)
Error: The process '/home/runner/work/_temp/a43267ea-e7ac-4bee-a1b7-a380fa042d18/maturin' failed with exit code 1