Testing: Add pyupgrade linting; #6538

Pyupgrade is a linter to check for deprecated Python syntax.
This commit configures ruff to perform pyupgrade linting.
In the ignore list, I added some pyupgrade error codes (UP*) for the
moment.
These must either be fixed manually, or might be controversial in some
way, so we can consider them at a later point.

pyproject.toml

@@ -38,12 +38,19 @@ exclude = [
 [tool.ruff.lint]
 select = [
     "I", # isort
+    "UP", # pyupgrade
 ]
 
 ignore = [
     "ALL",
+    "UP008", # Use `super()` instead of `super(__class__, self)`
+    "UP015", # Unnecessary open mode parameters
+    "UP027", # Replace unpacked list comprehension with a generator expression
+    "UP028", # Replace `yield` over `for` loop with `yield from`
+    "UP030", # Use implicit references for positional format fields
     "UP031", # Use format specifiers instead of percent format
+    "UP032", # Use f-string instead of `format` call
     "SIM210", 
 ]
 
-extend-safe-fixes = ["I001"]
+extend-safe-fixes = ["I001"]