The version that will be written to the NEEDED section depends on the SONAME of the linked library. That means the linker reads it from the file your /usr/lib/x86_64-linux-gnu/libnova.so ultimately points to. This has nothing to do with CMake, it’s how the linking works.
So you’d have to build libnova with appropriate SONAME. I do not recommend this however as it’ll break stuff sooner or later when whoever installs your software would have an incompatible version of libnova on their system.