CI: simplify os selection

.github/workflows/main.yml

@@ -53,17 +53,13 @@ jobs:
           cython-lint src/gstools/
 
   build_wheels:
-    name: wheels for ${{ matrix.cfg.os }} / ${{ matrix.cfg.arch }}
+    name: wheels for ${{ matrix.cfg.os }}
     runs-on: ${{ matrix.cfg.os }}
     strategy:
       fail-fast: false
       matrix:
-        cfg:
-        - { os: ubuntu-latest, arch: x86_64 }
-        - { os: windows-latest, arch: AMD64 }
-        - { os: macos-latest, arch: x86_64 }
-        - { os: macos-latest, arch: arm64 }
-        - { os: macos-latest, arch: universal2 }
+        # macos-13 is an intel runner, macos-14 is apple silicon
+        os: [ubuntu-latest, windows-latest, macos-13, macos-14]
 
     steps:
       - uses: actions/checkout@v4
@@ -72,8 +68,6 @@ jobs:
 
       - name: Build wheels
         uses: pypa/[email protected]
-        env:
-          CIBW_ARCHS: ${{ matrix.cfg.arch }}
         with:
           output-dir: dist
 
@@ -87,7 +81,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-13, macos-latest]
+        os: [ubuntu-latest, windows-latest, macos-13, macos-14]
         # https://github.com/scipy/oldest-supported-numpy/blob/main/setup.cfg
         ver:
           - {py: '3.8', np: '==1.20.0', sp: '==1.5.4'}
@@ -97,11 +91,11 @@ jobs:
           - {py: '3.12', np: '==1.26.2', sp: '==1.11.2'}
           - {py: '3.12', np: '>=2.0.0rc1', sp: '>=1.13.0'}
         exclude:
-          - os: macos-latest
+          - os: macos-14
             ver: {py: '3.8', np: '==1.20.0', sp: '==1.5.4'}
-          - os: macos-latest
+          - os: macos-14
             ver: {py: '3.9', np: '==1.20.0', sp: '==1.5.4'}
-          - os: macos-latest
+          - os: macos-14
             ver: {py: '3.10', np: '==1.21.6', sp: '==1.7.2'}
     steps:
       - uses: actions/checkout@v4