Rev cmake minimum version from 3.14.2 to 3.14.5 (#34757)

Rev cmake minimum version from 3.14.2 to 3.14.5 (#34757)

iOS requires 3.14.5 version and we have a special case for it. Since this is a minor version difference, and no distro is particularly providing cmake 3.14.2 package, it is safe to update to 3.14.5 to cover our supported platform matrix.

Discussion: https://github.com/dotnet/runtime/pull/33959#discussion_r396389297
Fixes: https://github.com/dotnet/runtime/issues/33976

Co-authored-by: Alexander Köplinger <alex.koeplinger@outlook.com>