Port some tests away from nose as examples (#33437)

We don't need to use both nose and pytest.  Once we get rid of all uses
of nose we can remove the extra dependency

test/units/modules/cloud/amazon/test_s3.py

@@ -5,8 +5,7 @@ import unittest
 try:
     import ansible.modules.cloud.amazon.s3 as s3
 except ImportError:
-    from nose.plugins.skip import SkipTest
-    raise SkipTest("This test requires the s3 Python libraries")
+    pytestmark = pytest.mark.skip("This test requires the s3 Python libraries")
 
 from ansible.module_utils.six.moves.urllib.parse import urlparse