Remove macOS 10.15 from CI

Azure is GH workflows are dropping it.

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

azure-pipelines.yml

@@ -26,8 +26,8 @@ jobs:
 
     - template: etc/ci/azure-posix.yml
       parameters:
-          job_name: macos1015_cpython
-          image_name: macos-10.15
+          job_name: macos12_cpython
+          image_name: macos-12
           python_versions: ['3.8', '3.9', '3.10']
           test_suites:
               all: venv/bin/pytest -n 2 -vvs