chore(ruff): Manual fixes for config_reader

src/tmuxp/config_reader.py:102:19: SIM115 Use context handler for opening files
src/tmuxp/config_reader.py:102:19: PTH123 `open()` should be replaced by `Path.open()`

Author: tony

src/tmuxp/config_reader.py

@@ -99,7 +99,7 @@ def _from_file(cls, path: pathlib.Path) -> t.Dict[str, t.Any]:
         {'session_name': 'my session'}
         """
         assert isinstance(path, pathlib.Path)
-        content = open(path).read()
+        content = path.open().read()
 
         if path.suffix in [".yaml", ".yml"]:
             format: "FormatLiteral" = "yaml"