fix(python): match Field signatures (#1463)

# Description

Field signatures are not identical on the `type` field, which makes
instantiating deltalake Fields with the `type` keyword impossible in
python - and the `name` keyword as well for that matter.

# Related Issue(s)
<!---
For example:

- closes #106
--->

# Documentation

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python/src/schema.rs

@@ -599,7 +599,7 @@ impl MapType {
 /// Field("my_col", PrimitiveType("integer"), nullable=True, metadata={"custom_metadata": {"test": 2}})
 #[pyclass(
     module = "deltalake.schema",
-    text_signature = "(name, ty, nullable=True, metadata=None)"
+    text_signature = "(name, type, nullable=True, metadata=None)"
 )]
 #[derive(Clone)]
 pub struct Field {
@@ -609,15 +609,15 @@ pub struct Field {
 #[pymethods]
 impl Field {
     #[new]
-    #[pyo3(signature = (name, ty, nullable = true, metadata = None))]
+    #[pyo3(signature = (name, r#type, nullable = true, metadata = None))]
     fn new(
         name: String,
-        ty: PyObject,
+        r#type: PyObject,
         nullable: bool,
         metadata: Option<PyObject>,
         py: Python,
     ) -> PyResult<Self> {
-        let ty = python_type_to_schema(ty, py)?;
+        let ty = python_type_to_schema(r#type, py)?;
 
         // Serialize and de-serialize JSON (it needs to be valid JSON anyways)
         let metadata: HashMap<String, serde_json::Value> = if let Some(ref json) = metadata {

python/tests/test_schema.py

@@ -170,7 +170,7 @@ def test_delta_field():
     # TODO: are there field names we should reject?
 
     for name, ty, nullable, metadata in args:
-        field = Field(name, ty, nullable=nullable, metadata=metadata)
+        field = Field(name=name, type=ty, nullable=nullable, metadata=metadata)
 
         assert field.name == name
         assert field.type == (PrimitiveType(ty) if isinstance(ty, str) else ty)