fix: Indent of generated code for non-required lists. Thanks @sfowl! (openapi-generators#1050)

The `_transform` macro is called at three different places in this file,
but one location was not similarly indented as the other two. This
caused errors in the ruff post_hook like:

```
error: Failed to parse foo/models/foo_request.py:125:9: Expected an indented block after `if` statement
```

The generated code without the indent fix looks like:

```
        if not isinstance(self.foo, Unset):
        _temp_foo = []  # <-- incorrect indent
            for foo_item_data in self.foo:
                foo_item: Union[None, int]
                foo_item = foo_item_data
                _temp_foo.append(foo_item)
            foo = (None, json.dumps(_temp_foo).encode(), 'application/json')
```

---------

Co-authored-by: Dylan Anthony <[email protected]>

Author: 2 people

end_to_end_tests/baseline_openapi_3.0.json

@@ -1961,6 +1961,14 @@
             "title": "Some Required Number",
             "type": "number"
           },
+          "some_int_array": {
+            "title": "Some Integer Array",
+            "type": "array",
+            "items": {
+              "type": "integer",
+              "nullable": true
+            }
+          },
           "some_array": {
             "title": "Some Array",
             "nullable": true,

end_to_end_tests/baseline_openapi_3.1.yaml

@@ -1970,6 +1970,13 @@ info:
           "title": "Some Number",
           "type": "number"
         },
+        "some_int_array": {
+          "title": "Some Integer Array",
+          "type": "array",
+          "items": {
+            "type": ["integer", "null"]
+          }
+        },
         "some_array": {
           "title": "Some Array",
           "type": [ "array", "null" ],

openapi_python_client/templates/property_templates/list_property.py.jinja

@@ -60,7 +60,7 @@ if not isinstance({{ source }}, Unset):
 {% else %}
 {{ destination }}: {{ type_string }} = UNSET
 if not isinstance({{ source }}, Unset):
-{{ _transform(property, source, destination, True, "to_dict") | indent(4)}}
+    {{ _transform(property, source, destination, True, "to_dict") | indent(4)}}
 {% endif %}
 {% endmacro %}