TestDirFSPathsValid fails on WASI on Windows?

When TestDirFSPathsValid is enabled on wasi, ```make tinygo-test-wasi-fast``` fails on windows as follows:
```
--- FAIL: TestDirFSPathsValid (0.00s)
    open C:\Users\RUNNER~1\AppData\Local\Temp\tinygotmp3373128602/TestDirFSPathsValid54961765/e:xperi\ment.txt: file does not exist
    FailNow is incomplete, requires runtime.Goexit()
    "." ok
    "." ok
FAIL
```