Also build installer for MacOS 11 in CI

Currently our CI is updated to MacOS 12, when building our installer/software the 12 SDK will be used, which can not be used on Macs with older versions of MacOS.

Question: Do we want to build both (more work) or only for 11 (less work)?

Use different deployment target: cmake -DMACOSX_DEPLOYMENT_TARGET=11.0 ...