DOC: OSX -> macOS (#43193)

Author: partev

doc/source/development/contributing_codebase.rst

@@ -181,7 +181,7 @@ run this command, though it may take longer::
 
    git diff upstream/master --name-only -- "*.py" | xargs -r flake8
 
-Note that on OSX, the ``-r`` flag is not available, so you have to omit it and
+Note that on macOS, the ``-r`` flag is not available, so you have to omit it and
 run this slightly modified command::
 
    git diff upstream/master --name-only -- "*.py" | xargs flake8
@@ -244,7 +244,7 @@ Alternatively, you can run a command similar to what was suggested for ``black``
 
     git diff upstream/master --name-only -- "*.py" | xargs -r isort
 
-Where similar caveats apply if you are on OSX or Windows.
+Where similar caveats apply if you are on macOS or Windows.
 
 You can then verify the changes look ok, then git :any:`commit <contributing.commit-code>` and :any:`push <contributing.push-code>`.