feat(CI): add gfortran-{14,15} on macOS

Author: rouson

.github/workflows/build.yml

@@ -30,6 +30,14 @@ jobs:
             compiler: gfortran
             compiler-version: 13
             fpm-compiler: gfortran
+          - os: macos-latest
+            compiler: gfortran
+            compiler-version: 14
+            fpm-compiler: gfortran
+          - os: macos-latest
+            compiler: gfortran
+            compiler-version: 15
+            fpm-compiler: gfortran
 
     steps:
       - name: Checkout code