Fixes PyPy build

Author: holm10

.github/workflows/build-test-wheel.yml

@@ -100,7 +100,7 @@ jobs:
         if: (matrix.os == 'macos-13') || (matrix.os == 'macos-14')
         run: |
             # Symlink the correct gfortran compiler 
-            ln -s $HOMEBREW_PREFIX/bin/gfortran-13 $HOMEBREW_PREFIX/bin/gfortran
+            ln -s $(brew --prefix)/bin/gfortran-13 $(brew --prefix)/bin/gfortran
             # Install OMP libraries
             brew install libomp
             # Link environments to env for later us with cibuildwheel