update macos-latest to macos-12

Author: RitvikKapila

.github/workflows/ci_tests.yaml

@@ -22,7 +22,7 @@ jobs:
           # x86 builds are only meaningful for Windows
           - os: windows-latest
             architecture: x86
-          - os: macos-latest
+          - os: macos-12
             architecture: x64
         python:
           - 3.8