Use TypeAlias where possible for type aliases (#7630)

stubs/chevron/chevron/main.pyi

@@ -1,7 +1,8 @@
 from _typeshed import StrOrBytesPath
 from typing import Any
+from typing_extensions import TypeAlias
 
-_OpenFile = StrOrBytesPath | int
+_OpenFile: TypeAlias = StrOrBytesPath | int
 
 def main(template: _OpenFile, data: _OpenFile | None = ..., **kwargs: Any) -> str: ...
 def cli_main() -> None: ...