{ci} MSVC 32-bit build doesn't run tests

I [added](https://github.com/asmaloney/libE57Format/pull/235) an MSVC 32-bit build to the CI, but it fails to link with conda's xerces-c. Either the conda version doesn't include 32-bit builds of xerces, or the CI isn't finding them.

If anyone is interested in 32-bit builds, please feel free to fix this and submit a PR.

Start with the MSVC 32-bit CI build added in pull request #235 and inspect its xerces-c link failure. Determine whether conda lacks a 32-bit xerces-c build or the CI job cannot find it; done means the job links successfully and runs its tests.

Written by the indexing model from the issue text.