Need to move our MacOS images to 11 or 12

```
##[warning]The macOS-10.15 environment is deprecated, consider switching to macos-11(macos-latest), macos-12 instead. For more details see https://github.com/actions/virtual-environments/issues/5583
```
See https://github.com/actions/virtual-environments/issues/5583. 
We need to move from macOS-10.15 to macos-11 or macos-12. 