Diagnostic output from `-v` switch should output to stderr

[jwodder]

Adding the -v/--verbose option to a command causes the resulting diagnostic output to be output to stdout, when normally such things should be output to stderr. This is in particular a problem for the auto version command, as the diagnostic output gets mixed with the regular output, making it impossible to use the output while also getting debugging information.

[yarikoptic]

we need to debug again and I was surprised to find this issue still open. Sounds like it should be trivial to address.

[hipstersmoothie]

@yarikoptic PRs welcome <3