Update Mac (M1 & Intel) LIBIRBEM with IGRF-14 coef.

As I was unable to locate Mac machines with gfortran installed already,
this commit here relies on compiling the code via GitHub actions on
image "macos-13" (Intel based) with gfortran-12, and on
image "macos-latest" (M1, apple silocon based) with gfortran-12.

The compile took place in forked repository,
https://github.com/thomas-nilsson-irfu/IRBEM/blob/e0235cae110d3f13d0c906ad46a86f7f48f0ea1b/.github/workflows/ci.yml
(the actual fortran code was fully in sync with github repo PRBEM/IRBEM at commit
8279aa9fd50c0a32d63efe762454b9ebf3b81ef6 at this time).

Details on GitHub runners:
macos-13 (Intel):
https://github.com/actions/runner-images/blob/39222c24c48e09beba42cd94c781b3a4d93dfd23/images/macos/macos-13-Readme.md

macos-latest (i.e. Apple silicon (M1), macos-14 at time of compile):
https://github.com/actions/runner-images/blob/39222c24c48e09beba42cd94c781b3a4d93dfd23/images/macos/macos-14-arm64-Readme.md