standardize packaging, tooling, docs, CI, and licensing

openapi_first/loader.pyi

@@ -1,8 +1,8 @@
 from pathlib import Path
-from typing import Any, Dict, Union
+from typing import Any
 
 from .errors import OpenAPIFirstError
 
 class OpenAPISpecLoadError(OpenAPIFirstError): ...
 
-def load_openapi(path: Union[str, Path]) -> Dict[str, Any]: ...
+def load_openapi(path: str | Path) -> dict[str, Any]: ...