Enable "UP" rules in Ruff (pyupgrade)

As version of Python get dropped (like Python 3.9 recently), it's good to keep on top of opportunities for syntax changes/modernization. This Ruff rule is an easy to way to do this.

My ulterior motive is to get more Ruff rulesets enabled in the codebase, gradually.

Author: nathanjmcdougall

pyproject.toml

@@ -82,3 +82,5 @@ namespaces = false
 [tool.ruff]
 line-length = 99
 exclude = ['tests/assets'] # These are sample packages for tests to run under - we don't want ruff to mess with them.
+[tool.ruff.lint]
+select = ["E4", "E7", "E9", "F", "UP"]

src/grimp/adaptors/caching.py

@@ -2,7 +2,6 @@
 
 import json
 import logging
-from typing import Optional
 
 from grimp.application.ports.filesystem import BasicFileSystem
 from grimp.application.ports.modulefinder import FoundPackage, ModuleFile
@@ -13,7 +12,7 @@
 from grimp import _rustgrimp as rust  # type: ignore[attr-defined]
 
 logger = logging.getLogger(__name__)
-PrimitiveFormat = dict[str, list[tuple[str, Optional[int], str]]]
+PrimitiveFormat = dict[str, list[tuple[str, int | None, str]]]
 
 
 class CacheFileNamer: