This commit increases the memory leak threshold for legacy_pcnt_driver
test from 300 bytes to 400 bytes. The test fails due to a breach of the
threshold value by 8 bytes.
This updates the minimal supported version of CMake to 3.16, which in turn enables us to use more CMake features and have a cleaner build system.
This is the version that provides most new features and also the one we use in our latest docker image for CI.
