Mojave support

Is there anything preventing SAP from using 5.1 to enable Mojave compilation?

```
// swift-tools-version:5.2
```

Start by checking the package's Swift tools-version declaration against the requested 5.1 compatibility and the Mojave compilation context. Determine whether the project can compile with that version, then document the compatibility result and verify the package builds on Mojave.

Written by the indexing model from the issue text.