chore(python): Test free-threaded in ci

Author: bschoenmaeckers

Diff for: .github/workflows/test-python.yml

@@ -39,7 +39,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        python-version: ['3.9', '3.12', '3.13']
+        python-version: ['3.9', '3.12', '3.13', '3.13t']
         include:
           - os: windows-latest
             python-version: '3.13'
@@ -48,7 +48,8 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        # TODO requires main: https://github.com/actions/setup-python/issues/771#issuecomment-2708960882
+        uses: actions/setup-python@main
         with:
           python-version: ${{ matrix.python-version }}
 

Diff for: crates/polars-python/src/conversion/datetime.rs

@@ -57,16 +57,16 @@ pub fn datetime_to_py_object<'py>(
                     .call1((v, tu.to_ascii(), time_zone.as_str()))
             } else {
                 let datetime = utc_datetime.with_timezone(&tz);
-                datetime.into_pyobject(py)
+                Ok(datetime.into_pyobject(py)?.into_any())
             }
         } else if let Ok(tz) = FixedOffset::from_str(time_zone) {
             let naive_datetime = timestamp_to_naive_datetime(v, tu);
             let datetime = tz.from_utc_datetime(&naive_datetime);
-            datetime.into_pyobject(py)
+            Ok(datetime.into_pyobject(py)?.into_any())
         } else {
             Err(PyPolarsErr::Other(format!("Could not parse timezone: {time_zone}")).into())
         }
     } else {
-        timestamp_to_naive_datetime(v, tu).into_pyobject(py)
+        Ok(timestamp_to_naive_datetime(v, tu).into_pyobject(py)?.into_any())
     }
 }

Diff for: py-polars/src/lib.rs

@@ -84,7 +84,7 @@ fn _expr_nodes(_py: Python, m: &Bound<PyModule>) -> PyResult<()> {
     Ok(())
 }
 
-#[pymodule]
+#[pymodule(gil_used = false)]
 fn polars(py: Python, m: &Bound<PyModule>) -> PyResult<()> {
     // Classes
     m.add_class::<PySeries>().unwrap();