Issues caused by code coverage in RuntimeHelpers.GetSpanDataFrom

[h3xds1nz]

With #10514 being merged in, a change was made to prevent CI builds from failing when using RuntimeHelpers.CreateSpan in one particular case in ContentType from WindowsBase here:

https://github.com/dotnet/wpf/pull/10514/files/a6cedcc7dce51a30caf60a3f07ec899fb8141f34#diff-1d02f80080e968e5fec25cef51809b5d0a9d18fce33cd7bd8fb2f9c75f14409aR665

This is caused by using outdated Coverlet version (3.1.2) which uses old version of Mono.Cecil. Coverlet is injecting methods to the assembly but the old version of Cecil has a bug with RVA alignment of packed fields, which causes it to fail at runtime when using CreateSpan. This was fixed in Mono.Cecil jbevain/cecil#817 and jbevain/cecil#888.

Coverlet uses Mono.Cecil containing those fixes since 6.0.0

[h3xds1nz]

fyi @singhashish-wpf