Stdin tests fail on windows/mac

[ruby0x1]

For now the following tests are skipped:

• test/io/stdin/read_byte_eof.wren
• test/io/stdin/read_line_eof.wren
• test/io/stdin/read_line.wren

On windows they time out, and on mac they have assertions. It seems the behavior of stdin is not consistent here (wren-cli code) or the test mechanics in python side (util/test.py) has differences. Given that the errors come from wren-cli side it's hard to tell since the code is the same.

Running the test manually via `bin/wren_cli test/io/stdin/read_line.wren) will work ok, because we're in a terminal typing on stdin.

[joshgoebel]

Point of recent data: I tested all 3 just now on Mac OS Mohave and all tests are green.

and on mac they have assertions.

I'm not sure I understand what you are saying here.