bumped macos version to latest and gcc version

Author: sanathkeshav

.github/workflows/build_and_test_mac.yaml

@@ -1,5 +1,5 @@
-name: Build and test macOS 15
-# Builds FANS for macOS 15 on Apple Silicon CPU and runs the tests.
+name: Build and test macOS
+# Builds FANS for macOS on Apple Silicon CPU and runs the tests.
 
 on:
   push:
@@ -15,8 +15,8 @@ concurrency:
 
 jobs:
   build-macos:
-    name: macOS 15
-    runs-on: macos-15
+    name: macos-latest
+    runs-on: macos-latest
     env:
       FANS_BUILD_DIR: build
     strategy:
@@ -28,9 +28,9 @@ jobs:
       - name: Install FANS dependencies
         run: |
           brew uninstall --force cmake
-          brew install gnu-time gcc@14
-          brew install open-mpi --build-from-source --cc=gcc-14
-          brew install hdf5-mpi --build-from-source --cc=gcc-14
+          brew install gnu-time gcc@15
+          brew install open-mpi --build-from-source --cc=gcc-15
+          brew install hdf5-mpi --build-from-source --cc=gcc-15
           brew install fftw eigen
 
       - name: Set up pixi
@@ -44,8 +44,8 @@ jobs:
       - name: Configure
         working-directory: ${{ env.FANS_BUILD_DIR }}
         env:
-          CC: gcc-14
-          CXX: g++-14
+          CC: gcc-15
+          CXX: g++-15
           MPICC: mpicc
           MPICXX: mpicxx
         run: |