`cmake_minimum_required` version is too old

Since the CMake 3.31 release, this warning is shown by CMake:

CMake Deprecation Warning at CMakeLists.txt:5 (cmake_minimum_required):
Compatibility with CMake < 3.10 will be removed from a future version of
CMake.

Update the VERSION argument value. Or, use the ... syntax
to tell CMake that the project requires at least but has been updated
to work with policies introduced by or earlier.

Gentoo is already emitting a QA warning when building packages that specify minimum CMake versions older than 3.10, as these packages will break upon an upcoming CMake release. See the Gentoo [tracker](https://bugs.gentoo.org/964405) for this issue.

**Please bump your `cmake_minimum_required` to some version ≥3.10.** Be aware that this will [change](https://cmake.org/cmake/help/latest/manual/cmake-policies.7.html#policies-introduced-by-cmake-3-10) some policy defaults.