Fix yaml syntax

Author: oscarbenjamin

.github/workflows/buildwheel.yml

@@ -11,7 +11,7 @@ jobs:
       fail-fast: false
       matrix:
         #os: [ubuntu-20.04, windows-2019, macos-13, macos-14]
-        os: macos-14
+        os: [macos-14]
 
     steps:
       - uses: actions/checkout@v4