Update AppVeyor config

[QuLogic]

PR summary

AppVeyor is quite slow, but is also the only CI to check the conda environment, so cut it down to only one Python version. But also enable a few more things to see if they work.

PR checklist

• [n/a] "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• [n/a] Plotting related features are demonstrated in an example
• [n/a] New Features and API Changes are noted with a directive and release note
• [n/a] Documentation complies with general and docstring guidelines

[QuLogic]

I tried enabling miktex and imagemagick, and though conda-forge has both of them, the latter doesn't seem to be available. And miktex fails with what seems to be a permission error. I tried to investigate over RDP, but couldn't find anything obvious other than maybe the package itself is missing some config files. So, we can try to enable that again later, and get the cut down setup in now.

[ksunden]

Hmmm... Exactly one SVG test is failing with a very small RMS (0.004)

[QuLogic]

Looking at the results, it's a small bit of text:

but this is not visible if you compare the .svg files directly. And it also seems to be 1 bit or so, as it's not particularly visible in the failed-diff.png output.

So I'll just add some fuzz on this one.