fix linter name

Author: vbvictor

llvm/utils/git/code-format-helper.py

@@ -467,7 +467,7 @@ def format_run(self, changed_files: List[str], args: FormatArgs) -> Optional[str
 
 
 class DumpASTMatchersHelper(FormatHelper):
-    name = "dump_ast_matchers"
+    name = "dump_ast_matchers.py"
     friendly_name = "AST matchers documentation"
 
     output_html = "clang/docs/LibASTMatchersReference.html"