Change default for Python version from 3.8 to 3.9 (#13896)

Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff_python_formatter/src/options.rs

@@ -457,10 +457,10 @@ where
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub enum PythonVersion {
     Py37,
+    Py38,
     // Make sure to also change the default for `ruff_linter::settings::types::PythonVersion`
     // when changing the default here.
     #[default]
-    Py38,
     Py39,
     Py310,
     Py311,