Update ci.yml, bump macos version

Author: fredroy

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-20.04, macos-10.15, windows-2019]
+        os: [ubuntu-20.04, macos-11, windows-2019]
         sofa_branch: [master, v22.06]
         python_version: ['3.8']