[CI] Build on MacOS broken due to CMake upgrade

[marcalff]

Compiling opentracing-cpp now fails, because it requires a very old CMake version.

CMake was upgraded to 4.1.1 with:

• [macOS] Cmake will be updated to version 4.* on September 8th actions/runner-images#12934

which no longer supports CMake < 3.5, causing a break.