tantivy: Disable a clippy warning about new not returning self.

The new() method using pyo3 does not return self, pyo3 handles some
python magic for us instead.

Disable the clippy warning about not returning self in new since it does
not apply to us.

src/document.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::new_ret_no_self)]
+
 use pyo3::prelude::*;
 use pyo3::types::PyDateTime;
 use pyo3::types::{PyDateAccess, PyTimeAccess};

src/index.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::new_ret_no_self)]
+
 use pyo3::exceptions;
 use pyo3::prelude::*;
 

src/schemabuilder.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::new_ret_no_self)]
+
 use pyo3::exceptions;
 use pyo3::prelude::*;
 

src/searcher.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::new_ret_no_self)]
+
 use pyo3::exceptions;
 use pyo3::prelude::*;