Fix SecurityInterface.Tests build in csproj.

The project would not build because the explicit reference to Monobjc.Security and Monobjc.SecurityFoundation conflicted with the implicit references from Monobjc.SecurityInterface.
Merge branch 'spicypixel/public/hotfix/remove-security-ref' of https://github.com/spicypixel/monobjc into spicypixel-spicypixel/public/hotfix/remove-security-ref