Update codebase to Python 3.10 using pyupgrade

kittens/diff/__init__.py

@@ -1,7 +1,4 @@
-from typing import Dict
-
-
-def syntax_aliases(x: str) -> Dict[str, str]:
+def syntax_aliases(x: str) -> dict[str, str]:
     ans = {}
     for x in x.split():
         k, _, v = x.partition(':')

kittens/diff/main.py

@@ -3,14 +3,13 @@
 
 import sys
 from functools import partial
-from typing import List
 
 from kitty.cli import CONFIG_HELP, CompletionSpec
 from kitty.conf.types import Definition
 from kitty.constants import appname
 
 
-def main(args: List[str]) -> None:
+def main(args: list[str]) -> None:
     raise SystemExit('Must be run as kitten diff')
 
 definition = Definition(