AppVeyor: update to use more recent Qt and MSVC
AppVeyor: update to use more recent Qt and MSVC

The last version of Qt to support MSVC 2015 is no longer maintained, so
I'm skipping that. I'm therefore rededicating MSVC 2017 for 32-bit.

There's also no more no-tests build.

thiagomacieira/tinycbor,thiagomacieira/tinycbor,thiagomacieira/tinycbor,thiagomacieira/tinycbor