tests: force `dummysmtpd.py` to write its log file with '\n' on Windows
The log files were being `cat'd` in `test-patchbomb-tls.t`, and causing
gratuitous failures. Since `sys.stdout` is being written to with `str` instead
of `bytes`, use a `io.TextIOWrapper` to change the EOL, like
2924676d4728.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf