[syntax-errors] type alias statements before Python 3.12 (#16478)

Summary
--
Another simple one, just detect standalone `type` statements. I limited
the diagnostic to `type` itself like [pyright]. That probably makes the
most sense for more complicated examples.

Test Plan
--
Inline tests.

[pyright]:
https://pyright-play.net/?pythonVersion=3.8&strict=true&code=C4TwDgpgBAHlC8UCWA7YQ

crates/ruff_python_parser/src/error.rs

@@ -449,6 +449,7 @@ pub enum UnsupportedSyntaxErrorKind {
     Match,
     Walrus,
     ExceptStar,
+    TypeAliasStatement,
     TypeParamDefault,
 }
 
@@ -458,6 +459,7 @@ impl Display for UnsupportedSyntaxError {
             UnsupportedSyntaxErrorKind::Match => "Cannot use `match` statement",
             UnsupportedSyntaxErrorKind::Walrus => "Cannot use named assignment expression (`:=`)",
             UnsupportedSyntaxErrorKind::ExceptStar => "Cannot use `except*`",
+            UnsupportedSyntaxErrorKind::TypeAliasStatement => "Cannot use `type` alias statement",
             UnsupportedSyntaxErrorKind::TypeParamDefault => {
                 "Cannot set default type for a type parameter"
             }
@@ -478,6 +480,7 @@ impl UnsupportedSyntaxErrorKind {
             UnsupportedSyntaxErrorKind::Match => PythonVersion::PY310,
             UnsupportedSyntaxErrorKind::Walrus => PythonVersion::PY38,
             UnsupportedSyntaxErrorKind::ExceptStar => PythonVersion::PY311,
+            UnsupportedSyntaxErrorKind::TypeAliasStatement => PythonVersion::PY312,
             UnsupportedSyntaxErrorKind::TypeParamDefault => PythonVersion::PY313,
         }
     }

crates/ruff_python_parser/src/parser/statement.rs

@@ -888,8 +888,22 @@ impl<'src> Parser<'src> {
     /// See: <https://docs.python.org/3/reference/simple_stmts.html#the-type-statement>
     fn parse_type_alias_statement(&mut self) -> ast::StmtTypeAlias {
         let start = self.node_start();
+        let type_range = self.current_token_range();
         self.bump(TokenKind::Type);
 
+        // test_ok type_stmt_py312
+        // # parse_options: {"target-version": "3.12"}
+        // type x = int
+
+        // test_err type_stmt_py311
+        // # parse_options: {"target-version": "3.11"}
+        // type x = int
+
+        self.add_unsupported_syntax_error(
+            UnsupportedSyntaxErrorKind::TypeAliasStatement,
+            type_range,
+        );
+
         let mut name = Expr::Name(self.parse_name());
         helpers::set_expr_ctx(&mut name, ExprContext::Store);