ci: host WiX 3.14.0.6526 binaries ourselves

Since commit 06c6e76a12 (ci: update to WiX 3.14.0.6526, 2022-06-10,
v3.24.0-rc1~4^2~2) we download the WiX binaries from `wixtoolset.org`
instead of a `github.com` CDN.  Avoid hitting their organization site
on every CI job by hosting the binaries at `cmake.org`.