Add Python 3 CI support. (#17209)

test/utils/shippable/python3-test-target-blacklist.txt

@@ -0,0 +1,14 @@
+s/ check_mode / /
+s/ environment / /
+s/ includes / /
+s/ no_log / /
+s/ pull / /
+s/ test_async_conditional / /
+s/ test_binary_modules$/ /
+s/ test_connection / /
+s/ test_handlers / /
+s/ test_hash / /
+s/ test_lookup_paths / /
+s/ test_var_precedence / /
+s/ test_vault / /
+s/ unicode / /