Add syntax error for empty type parameter list (#12030)

## Summary

(I'm pretty sure I added this in the parser re-write but must've got
lost in the rebase?)

This PR raises a syntax error if the type parameter list is empty.

As per the grammar, there should be at least one type parameter:
```
type_params: 
    | invalid_type_params
    | '[' type_param_seq ']' 

type_param_seq: ','.type_param+ [','] 
```

Verified via the builtin `ast` module as well:
```console    
$ python3.13 -m ast parser/_.py
Traceback (most recent call last):
  [..]
  File "parser/_.py", line 1
    def foo[]():
            ^
SyntaxError: Type parameter list cannot be empty
```

## Test Plan

Add inline test cases and update the snapshots.

crates/ruff_python_parser/src/error.rs

@@ -99,6 +99,8 @@ pub enum ParseErrorType {
     EmptyDeleteTargets,
     /// An empty import names list was found during parsing.
     EmptyImportNames,
+    /// An empty type parameter list was found during parsing.
+    EmptyTypeParams,
 
     /// An unparenthesized named expression was found where it is not allowed.
     UnparenthesizedNamedExpression,
@@ -242,6 +244,7 @@ impl std::fmt::Display for ParseErrorType {
             ParseErrorType::EmptyImportNames => {
                 f.write_str("Expected one or more symbol names after import")
             }
+            ParseErrorType::EmptyTypeParams => f.write_str("Type parameter list cannot be empty"),
             ParseErrorType::ParamAfterVarKeywordParam => {
                 f.write_str("Parameter cannot follow var-keyword parameter")
             }