gh-110558: Enable ruff's pyupgrade rules when running on Argument Clinic (#110603)

Tools/clinic/.ruff.toml

@@ -2,9 +2,24 @@ target-version = "py310"
 fix = true
 select = [
     "F",  # Enable all pyflakes rules
+    "UP",  # Enable all pyupgrade rules by default
     "RUF100",  # Ban unused `# noqa` comments
     "PGH004",  # Ban blanket `# noqa` comments (only ignore specific error codes)
 ]
+ignore = [
+    # Unnecessary parentheses to functools.lru_cache: just leads to unnecessary churn.
+    # https://github.com/python/cpython/pull/104684#discussion_r1199653347.
+    "UP011",
+    # Use format specifiers instead of %-style formatting.
+    # Doesn't always make code more readable.
+    "UP031",
+    # Use f-strings instead of format specifiers.
+    # Doesn't always make code more readable.
+    "UP032",
+    # Use PEP-604 unions rather than tuples for isinstance() checks.
+    # Makes code slower and more verbose. https://github.com/astral-sh/ruff/issues/7871.
+    "UP038",
+]
 unfixable = [
     # The autofixes sometimes do the wrong things for these;
     # it's better to have to manually look at the code and see how it needs fixing

Tools/clinic/clinic.py

@@ -2423,7 +2423,7 @@ def dump(self) -> str:
 
 def write_file(filename: str, new_contents: str) -> None:
     try:
-        with open(filename, 'r', encoding="utf-8") as fp:
+        with open(filename, encoding="utf-8") as fp:
             old_contents = fp.read()
 
         if old_contents == new_contents: