Bump minimum Python version to 3.8 (#1876)

* Bump minimum Python version to 3.8

* typing_extensions.Literal -> typing.Literal

* ns-dev-test

* typing_extensions.get_args => typing.get_args

* Format with older version of black

* Bump `black`

* Run black

scripts/texture.py

@@ -6,11 +6,10 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Optional
+from typing import Literal, Optional
 
 import tyro
 from rich.console import Console
-from typing_extensions import Literal
 
 from nerfstudio.exporter import texture_utils
 from nerfstudio.exporter.exporter_utils import get_mesh_from_filename