Pin cmake version

With cmake 4.0, compatibility with versions of CMake older than
3.5 has been removed. This makes it incompatible with this
cmake project.

https://cmake.org/cmake/help/latest/release/4.0.html#deprecated-and-removed-features

Since this branch is not actively worked on, the easiest solution
is probably to pin the version of cmake to an older 3.x release.

Change-Id: I45193379880b35a4741b152fdfb3f54f6cb72b21