Modify settings of action script

Author: mandli

.github/workflows/testing.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       fail-fast: false # Probably want to turn this off for a large matrix
       matrix:
-        os: [ubuntu-latest] #, macos-latest]
+        os: [ubuntu-latest, macos-latest]
         python-version: [3.12]
         build: [optimized]
         toolchain:
@@ -34,11 +34,13 @@ jobs:
           # - {compiler: lfortran, version: '0.45.0'} # Does not work with meson
         include:
           - os: ubuntu-latest
-            build: [optimized, debug]
-            python-version: [3.8, 3.12]
+            build: debug
+            python-version: 3.8
         exclude:
           - os: ubuntu-latest
             toolchain: {compiler: gcc, version: 15}
+          - os: macos-latest
+            toolchain: {compiler: gcc, version: 14}
 
     steps:
     - name: Set up Python ${{ matrix.python-version }}