GHA: Don't hide doctest output

[zware]

With -q, we don't get any real results from running the doctests.

[erlend-aasland]

This should be backported through the security branches.

[erlend-aasland]

On a second though, I'm not sure this is a good idea; previously we'd easily see the deprecation warnings that appear throughout the doctest suite. Now, we need to scroll a lot to see them.

Unsure about the change

[zware]

On a second though, I'm not sure this is a good idea; previously we'd easily see the deprecation warnings that appear throughout the doctest suite. Now, we need to scroll a lot to see them.

That's a point. I was going to suggest that we could set PYTHONWARNINGS=error for doctest, but that currently prevents it from running at all due to babel's dependence on cgi.parse_header.

[ambv]

If we wait for Babel 2.11, it got rid of the cgi dependency:
python-babel/babel#873

In this case I think setting PYTHONWARNINGS=error for doctest makes perfect sense.

However, we wouldn't be able to backport this beyond 3.10 I think as the sec-only versions have quite outdated documentation dependencies otherwise.

[zware]

I went ahead and fixed (or hid) existing warnings in the doctests and enabled warnings-as-errors via global doctest setup in Doc/conf.py to avoid any current or future warnings in Sphinx or its dependencies.

[zware]

I'm not sure whether this is worth a backport or not.