Run workflow on Windows, macOS and Linux

[jonahgraham]

This is to provide a test bench for #734 and to help prevent any fix for #734 from regressing.

[cdietrich]

@jonahgraham can you check if my patch works with that?

[nixel2007]

You could add macos too, cause it may have some os-specific behavior in uri and path handling (and yes, lsp4j is used on macos setups as part of bsl language server)

[jonahgraham]

@jonahgraham can you check if my patch works with that?

I am looking at that now - I couldn't get your patch to work, but #737 has an alternative I am trying to verify.

You could add macos too, cause it may has some os-specific behavior in uri and path handling (and yes, lsp4j is used on macos setups as part of bsl language server)

OK, will do.