Could not find module build/webview on OS X

I'm using Mojave 10.14.6.
I've tried to `jpm test` eihter with janet 1.15.3 and HEAD (both installed via homebrew).
I get this:
```

jpm test
running test/test.janet ...
could not find module build/webview:
/usr/local/Cellar/janet/HEAD-c909762/lib/janet/build/webview.jimage
/usr/local/Cellar/janet/HEAD-c909762/lib/janet/build/webview.janet
/usr/local/Cellar/janet/HEAD-c909762/lib/janet/build/webview/init.janet
/usr/local/Cellar/janet/HEAD-c909762/lib/janet/build/webview.so
in require-1 [boot.janet] on line 2528, column 20
in import* [boot.janet] on line 2567, column 15
in _thunk [test/test.janet] (tailcall) on line 3, column 1
```

Start by running `jpm test` on Mojave and inspect the import at line 3 of test/test.janet, using the listed module search paths as the initial clue. The work is done when the build/webview module is found and the test suite runs successfully.

Written by the indexing model from the issue text.